Added element IDs to Manage Clusters page

I added IDs to some Manage Clusters page elements to be able to be able to locate them properly using automated tests.

I also had to rewrite the method used to create buttons in Create Cluster dialog to specify IDs for them as well.

Convention used:

**\<page\_name\>\_\<element\_description\>** in a template
and/or
**\<action\>\_\<element\_type\>** in javascript