fixes #4768 - various activation key page issues

* Default content View was not selectable
* Using a paged API for content view dropdown (fixed across the app)
* Fixes environment selector on new activation key page, no disable option needed
* Updated text slightly on activation key page to make it more user friendly
Merge pull request #3901 from jlsherrill/akey_cv

fixes #4768 - various activation key page issues