UC-1155
http://track.sipfoundry.org/browse/UC-1155

Tracker addressed 2 issued:
- eliminate core dumps generated by unsynchronization between
sip services and mongo ( in case mongo hadn't finished its
initialization phases and sip services tried to use mongo a
core dump would have resulted)
- eliminate core dumps generated by mongo tcp opperations

First issue doesn't require fixing because
- proxy and registry return a 500 error message when sending a
request to mongo
- saa and rls check the connection with mongo. If the connection
isn't established then the service exits

Added class OsExceptionHandlerBase which has methods for handling
exceptions.
There are 2 exception handlers : a default one and a custom one
that is initialized with NULL (its behaviour can be modified by the
application by creating a class that extends OsExceptionHandlerBase
and overwrites the desired exception handling method)
In the catch_global function if the custom handler isn't defined
then the default exception handle methods are called.

- removed duplicated catch_global method from OsServiceOptions.h and
sqa/ServiceOptions.h
- replaced MONGO_assert with MONGO_wassert because MONGO_assert isn't
defined for the mongo version we are using 2.2.3