Make ROOTDIR determination more robust

Remove unused CLIENTDIR and replace it with a TESTDIR
(pointing to rootdir/keystoneclient/tests) and use
normpath for determining the full path of rootdir.

This change is needed if keystoneclient/ is a symlink
and etc/ is in a different directory hierarchy.

Change-Id: Ice9165ef25ec0200ccfb50c2f2f3121a136652a2
PEP 8 Public and internal interfaces

Define which interfaces are public and which are internal based
on PEP 8.

For reference, PEP 8 section is here:
http://www.python.org/dev/peps/pep-0008/#public-and-internal-interfaces

Change-Id: I14233796b7838b78fbd355014478f3e326542966
Merge "Make ROOTDIR determination more robust"