spin out AAM, CLM, SDM, ATM and related code to menpofit

#453 proposed a restructuring of `menpo` into a small, tightly focused core library with a collection of specialized libraries depending on this core. `menpo3d` now contains all the complex dependencies for 3D work, `menpodetect` is a small specialized package that adds object detection to the Menpo family, and with this PR, `menpofit` will be the library in which all fitting code (SDM, CLM, AAM, ATM) and related methods can be developed. This has a number of nice benefits:

1. **Remove some of the more specialized (and more confusing) aspects of menpo into a specialized package.** `OrthoPDM`s, `ModelDrivenTransform` and `DX`, `DL`, `DP` are nice interfaces that do a good job of keeping the code used in fitting clean, but they are highly specialized. This PR moves this complexity to menpofit keeping the core library focused

2. **Expensive unit tests removed from core** Our test suite is now much faster for core menpo.

3. **menpofit can iterate independently from the core library at a greater speed.** There are a number of re-factorings that we could make on the fit package - with this split we can make changes to `menpofit` in the confidence that we won't be fundamentally breaking things for other users of menpo.

From now on development of fitting algorithms in menpo will happen in the [menpofit](https://github.com/menpo/menpofit) repository.