Upgrades, remove saved version file on success

* created on_success method which upgrade
  script runs if upgrade succeed, don't
  fail upgrade in case of errors
* remove saved version files for all
  upgrades from working directories

It solves several problems:

1. user runs upgrade 5.0 -> 5.1 which fails
upgrade system saves version which we upgrade
from in file working_dir/5.1/version.yaml.
Then user runs upgrade 5.0 -> 5.0.1 which
successfully upgraded. Then user runs again
upgrade 5.0.1 -> 5.1, but there is saved file
working_dir/5.1/version.yaml which contains
5.0 version, and upgrade system thinks that
it's upgrading from 5.0 version, as result
it tries to make database dump from wrong
version of container.

2. without this hack user can run upgrade
second time and loose his data, this hack
prevents this case because before upgrade
checker will use current version instead
of saved version to determine version which
we run upgrade from.

Change-Id: I5e6ae6ba2ae2e60b9812e131d2a7c533f4a38ab6
Related-bug: #1349833
Merge "Upgrades, remove saved version file on success"