Release v0.1.6

Added:

• waffle.io page to documentation for project management overview

Fixed:

• Parse errors when RAML file would have empty mappings (Issue 30)
• Switch yaml.Loader to yaml.SafeLoader (Issue 26)
• Update documentation to reflect rearrangement of errors (Issue 27)
• Remove default parameter from being required for baseURIParameters (Issue 29)
• Pin mock library for tox tests (Issue 22)
• Experimenting with speeding up pypy tests within tox on Travis