Move PimpleTransform classes to separate file.

Change-Id: Id5d00164be88628f591331036a5dfd7a0e6dd593
Throw exception when incorrect constructor is used for Transform

The DeformationField transform type requires an image.

Change-Id: Ib7f7d73991d7c5dd6d5fb8ba90e735060fd5c647
Adding CommandHolder as private object to Transform file

Change-Id: I8d8735ba558f8d34b1791a8de40884eb2dd45a47
Adding BSplineTransform with basic constructor.

Adding BSplineTransform the the available transform types. Added basic
constructor which uses an image as input for a reference image.

Change-Id: I43335f23cb226f18feb0f6ea4fb20cb991ac3568
Adding testing of BSplineTrasform with wrong constructor.

Change-Id: I019fbd516a27e9364a356a349af6b51e2d52940a
Adding test of constructor of BSplineTransform

Change-Id: I5af9b1745e03a1377324d9b4a461a59db0f665fe
Merge topic 'SIMPLEITK-538_AddBSplineTransforms' into next

7e12da0d Adding test of constructor of BSplineTransform
b196b9c7 Adding testing of BSplineTrasform with wrong constructor.
c777e23a Adding BSplineTransform with basic constructor.
54a2dd98 Adding CommandHolder as private object to Transform file
9261de62 Throw exception when incorrect constructor is used for Transform
5a2b231a Move PimpleTransform classes to separate file.