minor changes
Merge branch 'params' of github.com:SheffieldML/GPy into params

Conflicts:
	GPy/kern/parts/prod.py
Merge branch 'params' of github.com:SheffieldML/GPy into params
Merge branch 'params' of github.com:SheffieldML/GPy into params
Merge branch 'params' of github.com:SheffieldML/GPy into params

Conflicts:
	GPy/kern/kern.py
	GPy/kern/parts/prod.py
Merge branch 'params' of github.com:SheffieldML/GPy into params
Merge branch 'params' of github.com:SheffieldML/GPy into params
Merge branch 'params' of github.com:SheffieldML/GPy into params

Conflicts:
	GPy/kern/_src/constructors.py
Merge branch 'params' of github.com:SheffieldML/GPy into params
some work on ep, and some messing with wher ethe derivatives are computed (in the model, not the inference