- See https://leap.se/code/issues/7536
- Actual root cause not identified yet

Since we need to write a file we have to consider whether we are
running in 'standalone' mode or not to use the right path prefix.

- Related: #7512

- Breaks tests in dependent repos like soledad otherwise,
  because server.key could not be found

to make simpler the import of the tx client

- Related: #7274

Since register and unregister cant be used without full zmq initialization,
it should make sense to also check flag for them.

Checking was done inside of emit method. Doing on emit function at
a module level makes it cleaner with less lines inside of check.

Change EventsClientThread behavior so it won't start anymore if
the events flag is set to False

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

this, together with the events server registration, was breaking the
events signalling on the client whenever it used ipc:// sockets.