IK bones should have Deform disabled

[jamestomk]

Describe the bug
All IK bones should have Deform disabled. Otherwise any other new mesh parented with auto-weight will be incorrectly affected by IK bones; should only be affected by FK bones.

To Reproduce
Steps to reproduce the behavior:

1. create or load a blend file with an existing MBLab Armature
2. Add a cube, position it near an IK bone
3. Parent the cube to the MBLab Armature with Automatic weights
4. note that Vertex Groups with IK are created
5. Put the cube in Weight Paint mode and select the IK group of the bone closest to the and notice that it has influence, and posing that bone will "distort" the cube.
6. visit the IK bone in pose mode and notice that "Deform" property is enabled. If you disable this and try this again with a new cube, it is no longer influenced by the IK bone, but only the FK bones.
7. visit the character mesh and notice that there are not IK vertex groups when MBLab does the parenting.

Expected behavior
All IK bones should have Deform disabled, so that IK bones move FK bones and only FK bones affect a mesh.

Screenshots