Description of problem:
There are dependencies among template versions so it is necessary so sort templates to delete and remove them from the latest version to oldest version.

Version-Release number of selected component (if applicable):
3.6 master, commit 4ba3589

How reproducible:
most of the time, the more templates in version chain, the more probable

Steps to Reproduce:
1. Create at least five versions of some template
2. Select all template versions and click remove, confirm

Actual results:
Some (older) templates was not removed, Operation Canceled dialog with text:

Error while executing action:

<templatename>:

    Cannot delete Base Template that has Template Versions, please first remove all Template Versions for this Template: t-vm1,t-vm1,t-vm1.

Expected results:
all versions are deleted