core, webadmin: remove name from template version

From now, the template.name for template versions will be the name of
the base template, and template versions will only use the version name.

in this patch:
- backend: make sure name of template version is the same as the name of the base
  template (ie. allow duplicate name for template base and its versions).
- backend + UI: dont check name already exist for template versions.
- UI: disable 'name' field on new template dialog for versions,
  this field will show the selected base name.
- UI: template grid - show 'version_name (version_number)' instead of
  'name (version_name)'.
- UI: show template version name for importing templates, on template
  sub tab of export domain, and on import template dialog.

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1075074
Change-Id: I27f26e7d196d1d2eebfe86e8aac886f3e6a8fc5e
Signed-off-by: Omer Frenkel <ofrenkel@redhat.com>