Add mysql extension for sql scripts (#3413)

samples/YAML/database.yml.mysql

@@ -0,0 +1,42 @@
+#
+# PRODUCTION
+#
+production:
+  adapter: mysql2
+  encoding: utf8mb4
+  collation: utf8mb4_general_ci
+  reconnect: false
+  database: gitlabhq_production
+  pool: 10
+  username: git
+  password: "secure password"
+  # host: localhost
+  # socket: /tmp/mysql.sock
+
+#
+# Development specific
+#
+development:
+  adapter: mysql2
+  encoding: utf8mb4
+  collation: utf8mb4_general_ci
+  reconnect: false
+  database: gitlabhq_development
+  pool: 5
+  username: root
+  password: "secure password"
+  # socket: /tmp/mysql.sock
+
+# Warning: The database defined as "test" will be erased and
+# re-generated from your development database when you run "rake".
+# Do not set this db to the same as development or production.
+test: &test
+  adapter: mysql2
+  encoding: utf8mb4
+  collation: utf8mb4_general_ci
+  reconnect: false
+  database: gitlabhq_test
+  pool: 5
+  username: root
+  password:
+  # socket: /tmp/mysql.sock