* issue #1250, replace {pre,post}-receive and update hooks with a single shell script that does not require custom hooks to be a sh-script
* issue #1250, make script posix compilant
* v23, add migration script to update {pre,post}-receive and update hooks
* migration: use a more common name and rename v23 to v26 to avoid conflicts
* gofmt'ed and added copyright header
* fix SyncRepositoryHooks to also sync wiki repos
Philippe Kueck