Ref: Introduce CommandInterface

Runners now typehint on the new CommandInterface rather than
AbstractCommand to allow different constructor strategies for Commands
Ref: classmap -> PSR4
Add: hhvm to travis builds
Rem: coveralls.io as it was very hit and miss
Mod: 151 lines Phing -> 28 lines Make: deps--
Mod: Travis -> Make
Add: Chained Command Colleciton