Remove unused prepare_commit_msg section

Change-Id: Ia22c40f2168927e4ff5e9a2c2092d832127ed226
Reviewed-on: http://gerrit.causes.com/35590
Reviewed-by: Shane da Silva <shane@causes.com>
Tested-by: Shane da Silva <shane@causes.com>
Update gemspec

Also remove unused hook files.

Change-Id: I2ef7083f768aa7bb9815b1167ed35241d6c80b52
Reviewed-on: http://gerrit.causes.com/35591
Reviewed-by: Shane da Silva <shane@causes.com>
Tested-by: Shane da Silva <shane@causes.com>