NEW Hook for `Member::registerFailedLogin`

Adding a hook for registerFailedLogin so that it is possible to add some custom logic when a user fails to login

Also rearranged the write as this function could hit the DB up to 3 times. Now it will me 0 or 1 times.
Merge pull request #2560 from TomSpeak/patch-2

NEW Hook for `Member::registerFailedLogin`
BUG: An enum field in the search panel model admin misses an option to not filter on that field
Merge pull request #2566 from NicoHaase/master

 BUG: An enum field in the search panel model admin misses an option to not filter on that field
Removed duplicate "quickfire" section in docs
Better definition of "pre-release" branch in docs
image cacheFilename checks for numeric strings

using JSON_NUMERIC_CHECK json_encode flag and avoid duplicate files
creation
Raised minimum PHP Veresion to 5.3.3