Adding support for Globs and easy dealing with directories

[nsomar]

The idea is to add support for globs and quickly iterating a directory. I think it would look very similar to how ruby solves that. Check the documentation for http://ruby-doc.org/core-1.9.3/Dir.html

We can think about translating the following ruby examples to swift

• Dir["/**"] expand the glob and return all the matching files
• Dir.chdir change the current directory
• Dir.foreach(directory) enumerates the files in the directory
• and so on...