Add file extensions support for major languages (#1478)

This adds aliases for file extensions of some major languages.

- `coffee` -> `coffeescript`
- `md` -> `markdown`
- `py` -> `python`
- `rb` -> `ruby`
- `yml` -> `yaml`

Author: ybiquitous

components/prism-coffeescript.js

@@ -88,4 +88,5 @@ Prism.languages.insertBefore('coffeescript', 'keyword', {
 
 delete Prism.languages.coffeescript['template-string'];
 
+Prism.languages.coffee = Prism.languages.coffeescript;
 }(Prism));

components/prism-coffeescript.min.js

@@ -225,3 +225,5 @@ Prism.hooks.add('wrap', function (env) {
 
 	env.content = Prism.highlight(code, grammar, codeLang);
 });
+
+Prism.languages.md = Prism.languages.markdown;

components/prism-markdown.js

@@ -60,3 +60,5 @@ Prism.languages.python = {
 };
 
 Prism.languages.python['string-interpolation'].inside['interpolation'].inside.rest = Prism.languages.python;
+
+Prism.languages.py = Prism.languages.python;

components/prism-markdown.min.js

@@ -138,4 +138,6 @@
 			}
 		}
 	];
+
+	Prism.languages.rb = Prism.languages.ruby;
 }(Prism));

components/prism-python.js

@@ -43,3 +43,5 @@ Prism.languages.yaml = {
 	'important': /[&*][\w]+/,
 	'punctuation': /---|[:[\]{}\-,|>?]|\.\.\./
 };
+
+Prism.languages.yml = Prism.languages.yaml;