Rename README.textile to README.md
Updated README to valid markdown syntax
Updated README 

README declared Google Collections Library as an dependency.
As the dependency was changed to Guava Libraries in the 5.7 release the README has had to be updated.
Merge pull request #107 from TwoStone/master

Updated Readme file
Merge branch 'master' of github.com:checkstyle/checkstyle into issue-92