and `plugin_dir` to README.md Fixes #9
fix a small bug in version recognition
Merge pull request #10 from ericbmerritt/next

a couple of cleanup commits
support non-tag based semver versions in rebar projects
Merge pull request #11 from ericbmerritt/next

support non-tag based semver versions in rebar projects
fix dialyzer error (and bug) in the rebar_vsn_plugin
refs should never be treated as integers
Merge pull request #12 from ericbmerritt/next

fix a couple of bugs in rebar_vsn_plugin