Release Candidate for v0.2.1

Release Notes of v0.2.1-rc0

Added

• csemver now supports adding versions csemver.parse("a.b.c") + csemver.parse("d.e.f")
• parse method added as a shortcut for csemver.csemver(version)
• prerelease and build fields to set prerelease and build-tag
• Introduced python2 support (maybe it will be dropped in the future)
• Added unit tests
• Added index operator to object, it is now possible to select specific parts with
  with a['major'], a['minor'], a['patch'], a['prerelease'], a['build']. The fields are also writeable.

Fixed

• csmver.parse does not had a default value
• some getters did not return a value

Changed

• incMajor, incMinor, incPatch are now chainable and support additional integer parameter to specify amount
• Added deprecation warning to setNumber
• a.number will return an string instead of an dict.