Activity Integration don't call every activity plugins

Do not return every time, otherwise all triggers like onBeforePost will just work on the first plugin and not on the other.
This patch will not fix the compatibility with the existing plugins because some are returning "true" for generic triggers.
It is also possible to get all values and return a merge of these, but the __call function must call every activity plugins.
I don't think this is working either. We need to go through all the activity integrations without returning anything. Return value isn't checked (it doesn't matter if the action succeeds or fails), so we can just remove return for good.

@obsidev can you update your pull to remove your new code and $rat variable from the line above?