Clarify private methods in Action.
Clarify private methods in Action.

Rename: 
* `didProcess` -> `_success`
* `didNotProcess` -> `fail`
orbitjs/orbit.js,SmuliS/orbit.js,jpvanhal/orbit-core,jpvanhal/orbit.js,jpvanhal/orbit.js,orbitjs/orbit-core,orbitjs/orbit.js,jpvanhal/orbit-core,SmuliS/orbit.js