The git provider now no longer checks out to a "deploy" branch by
default and now checks out to the branch (with a remote upstream) or
else checks out to a detatched head.
The prior behavior can be restored by using "checkout branch 'deploy'".
This also removes the SCM resource base class and replaces it with a
resource partial and does some internal reorganization.
It also introduces the RecipeDSLHelper for better functional tests and
cleans up the functional tests of the git provider.
Properties that were only ever implemented on the git provider were
removed from the subversion provider where they had been inherited from
the base class incorrectly.
Some additional env var handling was added to the subversion handler in
the process of sorting out the common properties, including HOME
handling for alternative users.
Signed-off-by: Lamont Granquist <lamont@scriptkiddie.org>