Add a form field option on registration views to alter states through a view. Adds Views Bulk Operations for setting registration state.

Correct capacity valiation for new registrations by passing ensuring that the resistration_status() is reset when validating the registration form.

#2058033 by levelos and dpolant: Fix registration_status() to return FALSE is a host entity does not have registrations enabled.

Multiple slots has been renamed to maximum capacity and changed from a
bool to a int value. Also fixes some other issues with the udpate
implementation.

adding hook_update_7104 to change multiple_slots boolean setting into maximum_spaces integer setting.

Shifting all references to event 'slots' to be event 'spaces' in both code and UI, to make the upcoming registration slots module more sensible.