This change parses through the file list in the perforce
changelist to pull branch information.  It looks like the
structure of our branches within the depot isn't something
that's universal to perforce, so this goes inside the
VMware-specific code, rather than the PerforceTool.

If a change touches more than one branch, these are stored
as a comma-separated list.

Added a check to the unit tests for VMwarePerforceTool, ran tests.