Clean up TerminationPointCreateCommand.java

This change abstracts the different steps involved in the
TerminationPointCreateCommand.execute() method so that the code is more
readable. The individual steps have been put into appropriate private helper
methods.

Change-Id: I65f0c8bc5da3a2509f42479a57fd0392c14baa5f
Signed-off-by: Ryan Goulding <ryandgoulding@gmail.com>