fixing unit tests for ctags from linux package
Merge pull request #3 from lzap/remove-ctags-test

Remove full path test for ctags command
Enable travis-ci
Update for RDoc 4 compatibility

This uses the argument-less #generate method
Update version
Only parse changed files when generating TAGS

This improves the speed of rdoc-tags for large projects.
Ignore ctags test on travis
Don't install ourselves before testing on travis
Sort vim definition output

On ruby 1.8 the output order wasn't reliable, some longer file names
would apper before shorter.
Allow string or symbol tag_style
Fix directory for ctags merge, tags task
Depend on ruby files in lib/