Added .reviewboardrc configuration file so a simple `rbt post` on a
branch will post a review to the Apache reviewboard. See `rbt --help`
for more details.
Tips:
rbt post # Create a new review of current branch with diff against master
rbt post --parent branchx # Review with diff against branchx instead of master
rbt post -r12345 # Post a new patch to existing review 12345
