Copied partition-related API from kickstart/custom_commands/partition.py
to separate module in preparation for removal of all
pykickstart related code.
(From OE-Core rev: a915c4cbc33ef0a12546ac0000ecf8aedb6241d5)
Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
