Once subscribed to publisher SUB socket gets collecting all incoming
messages that is unwanted behavior for fire-only events.
Fixed by using listen=<True|False> constructor argument.
* Raised max open files by 1024 since running in a vagrant machine 2048 was not enough, though, I think travis-ci defaults to a higher value.
* Wait a bit longer on the events testing.
* Separated the initial minions connected and minions synced into two different events and functions. Also corrected the `if` expected value when a timeout occurs.
* Test both master and minion events firing
* Allow targeting the minions in `tests.integration.ModuleCase.run_function()`
* The above item allows to also test events firing using `tcp` as `ipc_mode` which is being used by the tests `sub_minion`
