Merge branch 'release/1.3.0' into develop

* release/1.3.0:
  Bump version to 1.3.0
Add .rspec and spec_helper
Add clean rake task
Update for SemVer v2.0.0: bring library and tests up to date
Update README
Bump version to 2.0.0
Merge branch 'release/2.0.0'