Add ktlint

[ychescale9]

Resolves #10

PR adds ktlint throught the ktlint-gradle plugin.

I've fixed all issues reported by the default rules (except import-ordering which is inconsistent with Android Studio). Let me know if you want any specific rules disabled.

I also updated all dependencies in a separate commit and cleaned up unused ones.
Update: I'll do this in a separate PR as suggested.

Tested with ./gradlew assemble check.

There are still a bunch of kotlin compiler warnings e.g. missing @ExperimentalCoroutinesApi annotations which I can address in a separate PR.

[ychescale9]

I signed the CLA.

[yigit]

amazing, thank you!
can we add whatever check to the circle configuration as well so that we don't break this again.
Also, might be good to clear spotless or just limit it to copyright check?

[ychescale9]

I saw #5 and thought you might be switching to travis soon. But I'll update the circle ci config anyway.

Re. spotless I'll wait and see what @digitalbuddha thinks.

[changusmc]

@yarivkenan Thanks for the PR, would you mind splitting up "Add ktlint" and "Update dependencies" into separate PRs?

For the "Add ktlin" PR, can you update https://github.com/dropbox/Store/blob/master/CONTRIBUTING.md#coding-style to ask contributors apply Ktlint to either IntelliJ or githooks (i'm not sure which is better)

https://github.com/JLLeitschuh/ktlint-gradle#additional-helper-tasks

[digitalbuddha]

Thank you for the contribution!

[ychescale9]

Rebased with the following changes:

• reverted dependency updates (will create a separate PR)
• added instruction for generating IDE style files for ktlint
• applied ktlint plugin to allprojects instead of subprojects as ktlintApplyToIdea task is only added to the root project.

[digitalbuddha]

Do you mind doing the other diff you had as well? We can use some upgrades of dependencies :-)

[ychescale9]

yep, hang on for a minute.