add lint and warning checks

[eschrock]

Problem

We <3 clean code. In titan-server we run ktlint, and treat all warnings as error, to create a consistent style and expectations. We should do the same in the CLI.

Solution

Set the appropriate flags to treat warnings as errors, and add ktlint. See titan-server, though the mechanics will be difference since it's maven and not gradle.

Alternatives

Live with unclean code.

[mcred]

Was this resolved with #111?

[eschrock]

I added lint, but warnings still abound.