git bash completion updates for 1.5.3

The following changes since commit aabb2e515c334cbca9d9ae9873a188cef2c9b3ba:
  Eric Wong (1):
        git-svn: update documentation with CAVEATS section

are available in the git repository at:

  repo.or.cz:/srv/git/git/fastimport.git master

Shawn O. Pearce (3):
      Update bash completion with new 1.5.3 command line options
      Teach bash to complete ref arguments to git-describe
      Teach bash about git-submodule and its subcommands

 contrib/completion/git-completion.bash |   67 +++++++++++++++++++++++++++++---
 1 files changed, 61 insertions(+), 6 deletions(-)

Mostly really really trivial stuff.