Add a script to simplify some common developer workflows.

Add a script to simplify some common developer workflows.

Here are some example ways to use the script (from comments)

sync_build_test.sh
  syncs, recreates local repo and chroot, builds, and masters an
  image in the checkout based on your current directory, or if you
  are not in a checkout, based on the top level directory the script
  is run from.

sync_build_test.sh --image_to_usb=/dev/sdb -i
  same as above but then images USB device /dev/sdb with the image.
  Also prompt the user in advance of the steps we'll take to make
  sure they agrees.

sync_build_test.sh --top=~/foo --nosync --remote 192.168.1.2
  builds and masters an image in ~/foo, and live updates the machine
  at 192.168.1.2 with that image.

sync_build_test.sh --top=~/newdir --test "Pam BootPerfServer" \
     --remote=192.168.1.2
  creates a new checkout in ~/newdir, builds and masters an image
  which is live updated to 192.168.1.2 and then runs
  two tests (Pam and BootPerfServer) against that machine.

sync_build_test.sh --grab_buildbot=LATEST --test Pam --remote=192.168.1.2
  grabs the latest build from the buildbot, properly modifies it,
  reimages 192.168.1.2, and runs the given test on it.

[kdlucas, 2010-01-21 18:53:28]

LGTM

I didn't see any problematic errors in the script. With this many command line
options, you might consider using getopts, as this might simplify that part of
the code, and also it might be useful to create a usage() function and echo that
if they select --help or if their command line options are incorrect.