rename "enable" action to "toggle"

The previous action caused confusion when it was called "enable" in the
WebUI for both a disabled and an enabled user. It created an expectation
that its name would change when the state of the user would change.

Fixes bug 1202187

Change-Id: I620843df730520b55bfb709aaff1d63ce3f6e772
Fixing the AJAX function location

This bug addresses the incorrect location of the AJAX function call in api.py and moves it to the correct location in views.py
It also standardizes the AJAX JSON function to use a generic Django class instead of a function.

Change-Id: I445ca58d1e05187c9d05fdb6814039c69543324c
Fixes: bug #1201980
Remove all_tenants from server_list of Floating IPs tab

Change-Id: I050bdcccdc88c80b636f1061d60cc2dc5086d9b8
Fixes: bug #1203394
Merge "rename "enable" action to "toggle""
Merge "Fixing the AJAX function location"
Merge "Remove all_tenants from server_list of Floating IPs tab"