Replace collision_group_name with contact_shape_group_name

This makes it consistent with consistent with the contact_shapes property.
Rename old methods to getContactShapeGroupNames

RBM/getContactGroups and TSRBM/getCollisionGroups are now both named
getContactShapeGroupNames.

Resolves #408.
Merge pull request #442 from avalenzu/fix-getCollisionGroups

Fix get collision groups