Add predefined triggers

[Antondomashnev]

Hi all,

As I mentioned in #285 I'd like to propose another feature: add predefined triggers to Builda. The use case behind it that usually project has some common triggers such as install cocoapods, run fastlane, run danger, etc. And I think this will be a benefit during setup yet another syncer if the developer doesn't need to write it manually.

In the best case scenario, I'll expect these predefined triggers list constantly being increasing with PR from another developer with good useful scripts. This could be also the way to exchange the way developers set up their projects.

@czechboy0 what to do you think about this?

[czechboy0]

Agreed, I think this will be great.