Swap grammar used for CSS highlighting (#3426)

* Swap grammar used for CSS highlighting

* Whitelist license of Atom's CSS grammar

* Explicitly declare grammar as MIT-licensed

Source: https://github.com/atom/language-css/blob/5d4af/package.json#L14

vendor/README.md

@@ -76,7 +76,7 @@ This is a list of grammars that Linguist selects to provide syntax highlighting
 - **Csound:** [nwhetsell/language-csound](https://github.com/nwhetsell/language-csound)
 - **Csound Document:** [nwhetsell/language-csound](https://github.com/nwhetsell/language-csound)
 - **Csound Score:** [nwhetsell/language-csound](https://github.com/nwhetsell/language-csound)
-- **CSS:** [textmate/css.tmbundle](https://github.com/textmate/css.tmbundle)
+- **CSS:** [atom/language-css](https://github.com/atom/language-css)
 - **Cuda:** [harrism/sublimetext-cuda-cpp](https://github.com/harrism/sublimetext-cuda-cpp)
 - **Cycript:** [atom/language-javascript](https://github.com/atom/language-javascript)
 - **Cython:** [textmate/cython.tmbundle](https://github.com/textmate/cython.tmbundle)
@@ -84,7 +84,7 @@ This is a list of grammars that Linguist selects to provide syntax highlighting
 - **D-ObjDump:** [nanoant/assembly.tmbundle](https://github.com/nanoant/assembly.tmbundle)
 - **Dart:** [guillermooo/dart-sublime-bundle](https://github.com/guillermooo/dart-sublime-bundle)
 - **desktop:** [Mailaender/desktop.tmbundle](https://github.com/Mailaender/desktop.tmbundle)
-- **Diff:** [textmate/diff.tmbundle](https://github.com/textmate/diff.tmbundle)
+- **Diff:** [kivikakk/diff.tmbundle](https://github.com/kivikakk/diff.tmbundle)
 - **DM:** [PJB3005/atomic-dreams](https://github.com/PJB3005/atomic-dreams)
 - **DNS Zone:** [sixty4k/st2-zonefile](https://github.com/sixty4k/st2-zonefile)
 - **Dockerfile:** [asbjornenge/Docker.tmbundle](https://github.com/asbjornenge/Docker.tmbundle)

vendor/licenses/grammar/css.tmbundle.txt

@@ -1,15 +0,0 @@
----
-type: grammar
-name: css.tmbundle
-license: permissive
-curated: true
----
-
-If not otherwise specified (see below), files in this repository fall under the following license:
-
-	Permission to copy, use, modify, sell and distribute this
-	software is granted. This software is provided "as is" without
-	express or implied warranty, and with no claim as to its
-	suitability for any purpose.
-
-An exception is made for files in readable text which contain their own license information, or files where an accompanying file exists (in the same directory) with a “-license” suffix added to the base-name name of the original file, and an extension of txt, html, or similar. For example “tidy” is accompanied by “tidy-license.txt”.

vendor/licenses/grammar/language-css.txt

@@ -0,0 +1,36 @@
+---
+type: grammar
+name: language-css
+license: mit
+---
+Copyright (c) 2014 GitHub Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+--------------------------------------------------------------------
+
+This package was derived from a TextMate bundle located at
+https://github.com/textmate/css.tmbundle and distributed under the following
+license, located in `README.mdown`:
+
+Permission to copy, use, modify, sell and distribute this
+software is granted. This software is provided "as is" without
+express or implied warranty, and with no claim as to its
+suitability for any purpose.