Incubating warning opt out

[mockitoguy]

Problem

Currently, when I run Shipkit build I see 2 fat incubating warnings.

~/mockito/release$ ./gradlew
  Building version '0.9.59' (value loaded from 'version.properties' file).
  [INCUBATING] upgrade-dependency plugin is incubating and may change in any version.
  [INCUBATING] downstream-testing plugin is incubating and may change in any version.
:help

The make the build output untidy and reduces credibility of the library.

Suggested new feature

Let's add a feature to opt out from incubating warnings. For example:

shipkit { 
  incubatingWarnings.acknowlege "upgrade-dependency"
}

Above means that I acknowledge this incubating warning and I don't want to see it any more in the build log.

Suggested implementation

TBD. Do you have suggestions? :) If you want to work on this, let us know by commenting on this ticket!

[micd]

I would keep it simple.

1. Extend ShipkitConfiguration with new collection of acknowledged incubating warning
2. Extend IncubatingWarning#warn to accept ShipkitConfiguration
3. Check in IncubatingWarning#warn if plugin is acknowledged -- if not print warning

What do you think, @mockitoguy ?

[mockitoguy]

Based on discussion in #722, let's skip this idea. It adds complexity. Instead of hiding warnings, let's work on promoting features from "incubating" state to "release" state.

Thank you @micd for putting together the code. I hope you don't mind we won't take the PR at this time and we can cut more code together soon :)