Add a script for building and verifying release candidate

# example usage
$ bash dev-support/hbase-vote.sh -s https://dist.apache.org/repos/dist/dev/hbase/hbase-1.5.0RC2/

$ bash dev-support/hbase-vote.sh -h
hbase-vote. A script for standard vote which verifies the following items
1. Checksum of sources and binaries
2. Signature of sources and binaries
3. Rat check
4. Built from source
5. Unit tests

Usage: hbase-vote.sh -s | --source <url> [-k | --key <signature>] [-f | --keys-file-url <url>]
       hbase-vote.sh -h | --help

  -h | --help                   Show this screen.
  -s | --source '<url>'         A URL pointing to the release candidate sources and binaries
                                e.g. https://dist.apache.org/repos/dist/dev/hbase/hbase-<version>RC0/
  -k | --key '<signature>'      A signature of the public key, e.g. 9AD2AE49
  -f | --keys-file-url '<url>'   the URL of the key file, default is
                                http://www.apache.org/dist/hbase/KEYS