Fixed text on create cluster dialog

* In CreateCluster the action from cluster templates was used
* In jobs SelectHadoopPluginAction the template from cluster templates
  was used
* SelectPlugin and SelectPluginAction in jobs were never used.

Change-Id: I3affd88b49b36ec13e1a77f720bdad1da076fd7b
Closes-Bug:  bug #1336266
Co-Authored-By: Andrew Lazarev <alazarev@mirantis.com>
Fixed styling of ajax-animated bar

Did some css clean up as well. Removed the action_required_img class,
which is just a duplicate of the loading_gif.

Change-Id: I3f7f77d2b3ed56ff1c417241dc4b49ad763a1e81
Closes-Bug: #1349976
Fixed error message for recoverable exceptions

Issue was introduced by https://review.openstack.org/#/c/76354/
In case of recovarable exceptions message is None and exc_value
need to be used. But after encoding.force_unicode(message) message
becomes u'None' and all checks on "if message" pass. This result
in popup screen with 'None' text instead of problem description.

Change-Id: I7bc2dd02f97ba2bb10a7fadd2c1b86b011eb5967
Closes-Bug: #1350110
Verify Help button redirects to the right URL

When choosing "Help", in the top bar user drop-down menu,
the browser should redirect to http://docs.openstack.org/
Different distributions might customize the redirection URL,
but the above should be the default.

I added test_dashboard_help_redirection.py, go_to_help_page
method in basepage and the help_url value to horizon.conf
(also forced a change in config.py)

Partially implements blueprint: selenium-integration-testing
Closes-Bug #1350408

Change-Id: I64e661690ee9c26eb9d69092024465ab1c15b8a1
Merge "Fixed styling of ajax-animated bar"
Delete Stacks button doesn't work

Clicking on causes a frozen grey overlay.
It should have the class 'btn-danger' and remove the 'ajax-modal' class.

Change-Id: I892f7cc550cb1c332fa37fd08022b4d252918619
Closes-Bug: #1350112
Merge "Verify Help button redirects to the right URL"
Merge "Fixed error message for recoverable exceptions"
Merge "Fixed text on create cluster dialog"
Merge "Delete Stacks button doesn't work"