Allow apiCheck to run on all subprojects before failing

[OscarSpruit]

Issue

Currently, when you make changes to multiple modules, then apiCheck will fail on the first module where the API contract breaks.

Expected behaviour

When running apiCheck every module should be checked before failing. The output should accumulate all changes in the public API, so you get an overview of all changes in the project.

Additional info

Version: 0.14.0

[JakeWharton]

The --continue flag is a general-purpose mechanism that runs all possible tasks before failing at the end. I'm not sure it makes sense for every plugin to attempt to duplicate this behavior.

[OscarSpruit]

Thanks @JakeWharton! That should work and by processing the output I can format it nicely into a single overview.

If it's not desired for this plugin, maybe it's worth it to document this flag as I'm sure more people are unaware of this.