unittest2 was needed for Python versions <= 2.6, so it has not been
needed for quite some time now. See unittest2 note on:
https://docs.python.org/2.7/library/unittest.html
This drops unittest2 in favor of the standard unittest package.
Change-Id: I40882f14ff2ac121764b432fc745b21ae751e321
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>