Update README.md

Added usage note for Rails 4.
source plugin update to 0.3.9 and less->scss rename
remove auto apply to be able manually initialized
Merge pull request #4 from szyablitsky/master

Source plugin update to 0.3.9 and less->scss rename
update to 0.4.1
update to 0.4.2
Merge pull request #2 from moflo/patch-1

Update README.md
Merge pull request #6 from tsai146/update-0.4.1

update to 0.4.2
bumped up to 0.4.2.1 with updated README.md.
Merge remote-tracking branch 'upstream/master'