Added support for the Translation3D-type IK

Modified the ikfast moveit template to work with OpenRAVE's
Translation3D-type IK. This is useful for manipulators with few DOF
(i.e., 3 or 4) that just want to go to a certain position without caring
so much about the end effector's orientation.
Merge pull request #25 from sjlevine/translation3d

Added support for the Translation3D-type IK