Restored spam prevention

closes #3128
- added spam prevention middleware
- restored tests
Fix tests failing because of spam protection

closes #3128 (now really)
- added express variable disableLoginLimiter
- added disableLoginLimiter to all tests that use Ghost as module and
do authentication
- fixed isSetup not working for status other than active
- removed ‚Ensure a User is Registered‘ test as this is covered by the
new setup test
Merge pull request #3310 from sebgie/issue#3128-2

Fix tests failing because of spam protection