slt-changelog: --version & --sumary work together

Using "--summary --version X.Y.Z" now generates output suitable for
piping to `git commit -F-` for the version change commit.

Also cleanup old copy/paste code for supporting working outside of a
git repo.
Add usage to 'slt version'
slt-release,finish,start: gitflow release tools

These tools implement the gitflow release process, auto-generating the
changelog and setting the npm package version.
Merge pull request #7 from strongloop/feature/gitflow-release-tools

slt-release-finish,start: gitflow release tools
slt-release-finish: use the same tag in all places
Fix incorrect use of backticks
Merge pull request #9 from strongloop/fix/release-finish

slt-release-finish: use the same tag in all places
Remove unused second argument to shift

It came from the man page example from getopts, but seems to be an
error, shift doesn't take another argument.
Merge pull request #11 from strongloop/fix-shift-call

Remove unused second argument to shift
Annotate release tags with changelog

Uses slt-changelog to generate brief release notes for embedding
directly into the tag annotation, which conveniently show up in GitHub
as psuedo-releases, which partially addresses #8.
v1.2.0
Merge branch 'release/1.2.0' into production