[TIMOB-9144] Push notifications

Details in [Jira](https://jira.appcelerator.org/browse/TIMOB-9144)

**IMPORTANT** Must wait for [this PR](https://github.com/appcelerator/titanium_mobile/pull/5164) to be merged before merging this one

**Instructions** In [this link](https://gist.github.com/pec1985/8ad59783cd5b4adc45a2)