Add command line options and configurable constraint

The --version_constraint cli option allows for constraint on either
minor or patch level for versions.

Paired with Alex Riabov!
Fix integration tests from changing default version constraint
Add constraint level to version mapper
Add cli usage help and backup options

Also modify output to be more concise and descriptive.
Fix integration tests for jruby
Update version number to 0.1.0 and update HISTORY and README