Merge pull request #5 from no-reply/master

Implements persistence, un-manifested tag files, payload-oxums.
update to current spec version; update homepage and authors list
change contact email to me
removed oxums from todo list
add rvm, travis config, and change version to pre
add travis to README.md
use ruby 1.9 only in CI until 1.8.7 support is added
add 1.9.2 to travis jobs
need to require date for ruby 1.9.2
use File.size as a class method for 1.8.7 support
add 1.8.7 back to CI
update readme to match bagit.rb on spec version