If configured, we now check the IP address of the user signing up and, if they are a possible threat, we further reduce their number of allowed maximum builds to the configured value.
Fixes namespace validation to use the proper regex for checking length, as well as showing the proper messaging if the entered namespace is invalid
[Delivers #137830461]
Before this change, external auth such as Keystone would fail if a user without an email address tried to login, even if the email feature was disabled.
