Support gradle build cache

[sinwe]

When a particular module doesn't have any modified source code, there is no need to run scalastyle on that module. Gradle already have build cache for this. Could this plugin leverage on that cache? It will greatly reduce our total build time.

[jacobilsoe]

Is this not the same as issue #21?

[sinwe]

Perhaps. Not sure if #21 is related to gradle build cache

[jacobilsoe]

No, not specifically. It is more related to running scalastyle incrementally.

[sinwe]

Then it is different issue

[dsilvasc]

Right, it's different. See this example output:

> Task :...:scalaStyle UP-TO-DATE
Build cache key for task ':...:scalaStyle' is 364ed5531f68bcb2bc56e4b1543c8547
Caching disabled for task ':...:scalaStyle': Caching has not been enabled for the task
Skipping task ':...:scalaStyle' as it is up-to-date.
:..:scalaStyle (Thread[Task worker for ':' Thread 3,5,main]) completed. Took 0.001 secs.