Multi-disk support in vm_wizard added.

A user can now create a virtual machine instance and/or template which has
multiple disks when using the vm_wizard. The default max number of disks you
can add is 6, but this can be adjusted in settings.py.

refs #11995
Adding CSS to disks for javascript
Add Javascript for dynamic hiding and showing inputs

Move inline CSS into its own file.

Update base template html doc string for HTML5

refs #11955
Fix error messages for disks

refs #11955
Remove HTML5 docstring

refs #11955
vm-form: cleaned up some unnecessary comments
Merge branch 'enhancement/11955' into develop
Check for readonly privs on clusters

refs #11457
Merge branch 'enhancement/11457' into develop

* enhancement/11457:
  Check for readonly privs on clusters