Added "defaultbranch=master" to .gitreview file.
Also modified Policy CSITs to get the branch from the .gitreview
file instead of hard-coding it in a config file.
Issue-ID: POLICY-2597
Change-Id: I05e969d3efdaf09c4fca4012131983ca26423ab0 Signed-off-by: Jim Hahn <jrh3@att.com>