Add parameters to scale estimators

Change-Id: I1aadc0d21b7bce414514bd6ce1a4b1472a1d3e17
Set Sampling strategy for method

Change-Id: Iac2f48b243357c8f97946caccfbe111d889e3f90
Fix casting for strategy enum to itk type

Change-Id: I918becfe636cba6c5f8532158be5c1174f01c5ac
AddProcessObject::ToString method to print active process object

This method is called by the RegitrationMethod to enable debugging of
what's going on during execution. Other Filters should also added this
superclass call.

Change-Id: I7b3de7f699adb3d12a28a3d004ba029a44dfd10a
WIP: add LBFGSB opt 1
WIP: add LBFGSB 2
WIP: finish LBFGSB