Add programming languages

[ryanmjacobs]

Add programming languages to the list of extensions because they often have copyrights as well.

For example, a C file:

/**
 * progam.c
 * Author: John Doe
 * Copyright (c) 2014
 */

Pros

This won't break anything. 😄

Cons

The GitHub API limits users to 5,000 requests per hour. https://developer.github.com/v3/#rate-limiting
Adding more file types will use up more requests; although, this shouldn't be a problem for most users. Users with larges repositories may not be able to fully update their files before reaching the rate limit.