Existing helm.sh/hook-delete-policy annotation variables (hook-failed, hook-succeeded) do not allow to leave failed jobs for debugging without blocking the next job launching: every failed job must be deleted manually before the next related release is launching (installing, updating or rolling back).

New policy, before-hook-creation, removes the hook from previous release if there is one before the new hook is launched and can be used with another variable.

When "helm.sh/hook-delete-policy: hook-succeeded" is provided in a hook's annotation, Tiller will automatically delete the hook after the hook is succeeded. When "helm.sh/hook-delete-policy: hook-failed" is provided in a hook's annotation, Tiller will automatically delete the hook after the hook is failed.

Closes #1769

closes #2136
* Adds new annotation `helm.sh/hookWeight`
* Sorts executing hooks of similar kind in ascending order
* There is no upper or lower bounds on the weights

* resolves #1973

resolves #1927