* fixes async_handler_wrapper

adds missing runner variable from async to async_handler_wrapper
removes redundant have_async definition in wrap_async_run, defined at top of module

* only use async handler wrapper,
remove async_wrap_run

There are modules that will not work with prosody 0.10 as they depend on util.async. Adds a safeguard and print error about it in the logs.
And others that just do not work because of the muc module API that they use.

use optional prefix in poltergeist room lookup

The original presence stanza generation code for a poltergeist
has been re-factored and simplified a bit. Every time a
poltergeist presence is updated we first check that the poltergeist
still exists.

Previously a new call id was generated for INVITE and CANCEL.
Now the id generated during the initial INVITE will be used for
corresponding CANCEL events. Also, adding the ability to
trigger a call cancel via the poltergeist update api.

set up async context for all poltergeist calls
utils lib now has async wrapper for event handlers

If we do not reuse previous presences we lose avatar and name and people joining after the poltergeist creation will not be updated with those values.

Adds http method to remove poltergeists. Adds configurable timeout after which poltergeists automatically are removed from the room.

Thanks to Matthew Wild for the initial help of creating these.
Module with REST interface to create poltergeist participants and change their statuses.
When user with same id joins the room, the poltergeist is removed.  We also make sure that that user uses same username when authenticates. This way we are sure that user will join the room with the same nick as the poltergeist.