Support for non .md files

GitHub Wikis and Gollum support a number of markup formats with different file extensions. Currently using things other than .md causes the script to function abnormally.

Here's the list from the Gollum readme: .asciidoc, .creole, .markdown, .mdown, .mkdn, .mkd, .md, .org, .pod, .rdoc, .rest.txt, .rst.txt, .rest, .rst, .textile, .mediawiki, .wiki

[MarioRicalde]

I like this proposal, quick questions:

1. The generated files should be compiled on something other than .md files?
2. Should we allow end-user to mix different file types?

Cheers

I can see people having multiple types in one wiki. An example use case is a sysadmin docs wiki for a company. Each development team would maintain docs in the wiki for on call engineers to consult regarding their systems. Different teams may prefer to use different markup formats.