Replaces always disabled context selection link

In the context selection dropdown, there is currently an always disabled
link to do more advanced filtering. The original intent was to open a
modal to do more advanced context selection. With the use of RBAC in a
previous bp, the Identity->Projects panel is always accessible. This
panel provides the entire project list for the user. We can just use
this to provide the larger project list to select from.

Change-Id: I0d6674e75785206f3be48c8bf004a29906bb6860
Closes-Bug: #1382650
Missing a closing semicolon in _configure_general_help.html

This fix adds missing semicolon in _configure_general_help.html file
for &quot entity.

Change-Id: I04e0a806c6ed2d69be099992c7785129cced8829
Closes-Bug: 1386604
Guard against `None` value of User.email attribute

If email was not specified during User creation (it's not required),
it will be `None`. It would be safer to guard against already existing
`None` values than to prevent creating new user with email == `None`.

Change-Id: Id81a94491918190ceae4b08cd3293250bb4ab194
Closes-Bug: #1383630
Merge "Missing a closing semicolon in _configure_general_help.html"
Merge "Guard against `None` value of User.email attribute"
Merge "Replaces always disabled context selection link"