Remove old drivers dead code

This patch removes the notify_send code and some common helper method/class.
Because they are not used anymore by current amqpdriver.

Change-Id: I183750e158e05cf1d0b5e37725676d4882e0c043
Add transport reconnection retries

When a rpc client try to make a RPC call and the server is unreachable
The rpc call hang until the server come back.

In most case this is the desired behavior.

But sometimes, we can prefer that the library raise an exception after a
certain number of retries.

This patch allow this.

Closes bug #1282639

Change-Id: I32086d0abf141c368343bf225d4b021da496c020
Implements notification-dispatcher-filter

This patch allow to define a filter into an endpoint like this:

class WarnHandler(object):
    filter = NotificationFilter(publisher_id='^compute.*')

Implements blueprint notification-dispatcher-filter

Change-Id: Ic1239422fac9879b113c9d3d6c3f8dccef20d044
Full support of multiple hosts in transport url

This patch add the support of multiple hosts in transport url for rabbit and
qpid drivers. And also fix the amqp connection pool management to allow
to have one pool by transport.

Implements blueprint multiple-hosts-support-in-url

Change-Id: I5aff24d292b67a7b65e33e7083e245efbbe82024