refactor/get_rid_of_sleeps

[JarbasAl]

as mentioned in #53 we have a few places with hardcoded sleeps

these should be refactored out where possible, usually we can listen to (or add a new) bus event

do_a()
sleep(1)
do_b()

becomes

self.bus.once("bla", do_b)
do_a()

the new bus event will need to be sent from GUI side in some places of OCP

[JarbasAl]

more generically, i think we need to support some callback in self.gui.show_page for when page actually finished loading

{
    "type": "mycroft.events.triggered",
    "namespace": "mycroft.weather",
    "event_name": "page_gained_focus",
    "data": {"number": 0}
}

the above should be enough and is define in GUI transport protocol, ovos-gui should emit 'gui.page_gained_focus' when this happens which we can listen for