Fix hop dependencies

hop v0.27.0 is not compatible with bot_io v0.26.0, even though the
pubspec allows it.

We need to manually specify the max bot_io version if we want tests
to pass.
Add travis integration
Remove master only restriction
Quiet travis-lint
Merge pull request #1 from ajlai/fix-hop-dependencies

Fix hop dependencies
Bump version to 0.3.0