Fixed markdownlint warnings
Formatting
Merge pull request #52 from miniBill/patch-1

Formatting
Fixed url in 'obsolete' template
Added Vagrantfile
"Source Code Repository" page: fixed some links and removed outdated stuff
fixed typo
Changed Linux installation guide to recommend getting the key from a keyserver

This is better than getting the key from Mono's download server over http.
Fixes #53. Thanks to @eropple for help and the initial proposal.
Merge pull request #55 from marat-turaev/patch-1

Fixed typo on Garbage Collection - Sgen page
added Travis CI