Add --dev option (dev mode)

In dev mode delorean does a number of things differently to make it
easier for people to test packaging changes
o Builds arn't committed to the database so if run a second time delorean
  will rebuild a RPM even if it has already seen it.
o Don't do any git operations on the packaging repository so local
  changes are maintained between runs, this allows the packager to run
  delorean multiple times with having to commit changes in order to
  test them.
o The public delorean repository is installed in the build image. This
  will allow people to worry about a single package without having to
  build all of its dependencies.

Change-Id: Id62b6e6539afc539e7226c75f57505276c958eb1
Merge "Add --dev option (dev mode)"