to make simpler the import of the tx client

- Related: #7274

The connectTimeout parameter of twisted.web.client.Agent only acts on the
connection setup, and the Agent will wait forever for incoming data after the
connection has been established.

This commit adds a timeout for the connection, and will cancel the deferred if
the result has not been received after a certain number of seconds.

this will be used to allow the unittests to disable the events
framework. this way, emit() will become a passthrough.

note that, until now, the basetest class is making use of the threaded
version of the client, which launches a zmq tornado-based ioloop. this
is wrong, and will have to be addressed in a future commit. we'll have
to make use of the global EVENTS_ENABLED flag in the txclient version
when those changes are made.

Related: #7259
Relases: 0.4.2

The emission of an event was being logged twice, and the second time was
logging the pickled content of the event. This pickled content contained line
breaks and other things that caused strange output on the client log.

This commit removes the second loggin of the event pickled content.

Closes #7130.

previous regex wasn't capturing addresses of type ipc://<path>

Closes: #7089

Tag leap.common version 0.4.0