Add vendor patterns for bower_components files

Adds Bower Component files to the vendored files list.  This
uses the `bower_components` directory, which is the standard set by the
Bower package manager.

lib/linguist/vendor.yml

@@ -27,6 +27,9 @@
 # Node dependencies
 - node_modules/
 
+# Bower Components
+- bower_components/
+
 # Erlang bundles
 - ^rebar$