* Change graceful to use a singleton obtained through GetManager instead of a global.
* Graceful: Make TestPullRequests shutdownable
* Graceful: Make the cron tasks graceful
* Graceful: AddTestPullRequest run in graceful ctx
* Graceful: SyncMirrors shutdown
* Graceful: SetDefaultContext for Xorm to be HammerContext
* Avoid starting graceful for migrate commands and checkout
* Graceful: DeliverHooks now can be shutdown
* Fix multiple syncing errors in modules/sync/UniqueQueue & Make UniqueQueue closable
* Begin the process of making the repo indexer shutdown gracefully
* Graceful: Create callbacks to with contexts
* Graceful: Say when Gitea is completely finished
* Graceful: Git and Process within HammerTime
Force all git commands to terminate at HammerTime
Force all process commands to terminate at HammerTime
Move almost all git processes to run as git Commands
* Graceful: Always Hammer after Shutdown
* ProcessManager: Add cancel functionality
* Fix tests
* Make sure that process.Manager.Kill() cancels
* Make threadsafe access to Processes and remove own unused Kill
* Remove cmd from the process manager as it is no longer used
* the default context is the correct context
* get rid of double till
* Pre-caculate the absolute path of git
* Do not repeat string literals which has been defined somewhere
Also make it flexible to accept customized/user-defined value.
