Adding support for .command file ext for bash lang

The default double-clickable executable bash file extension in OS X is
.command. This PR should add bash syntax highlighting to .command files
by default.

Author: kethinov

src/language/languages.json

@@ -229,7 +229,7 @@
     "bash": {
         "name": "Bash",
         "mode": ["shell", "text/x-sh"],
-        "fileExtensions": ["sh"],
+        "fileExtensions": ["sh", "command"],
         "lineComment": ["#"]
     },