Revised SignalSlot component to preserve all handler return values.
Revised SignalSlot component to preserve all handler return values.

The emit methods now capture handler return values in a new
ResponseCollection object and return the entire collection.

The ResponseCollection class extends from SplStack and adds a few
convenience methods: first(), last() and contains(). The contains
method takes a value and checks if any of the response match the
given value.

Updated SessionManager to expect the new return behavior.

Updated and extended SignalSlot tests as appropriate.

Maks3w/zend-session,zendframework/zend-session,MadCat34/zend-session,oswaldderiemaecker/zend-session