List projects by scanning the managed Git directory

Rather than locating projects in the database table, perform a
recursive scan of the managed repository directory and pull up
anything that we find.  This is a first step towards moving all
the project control metadata directly into Git.

Bug: issue 436
Change-Id: I08e0083f14f5c03eb9e49b4895c265d13b828534
Signed-off-by: Shawn O. Pearce <sop@google.com>
13 files changed