[WIP] Migrate to Gradle

[Prof-Bloodstone]

Initial PR migrating ACF to gradle. It compiles - but would need to be checked further. All feedback welcome!

Things to do:

1. Configure shading as per original root project pom
2. Configure dependency-reduced pom
3. Check if I didn't miss anything (mostly automatic migration)
4. Make travis use gradle instead of maven
5. Delete all pom.xml files
6. Cleanup .gitignore?
7. Downgrade bungee API version back to 1.13 - it was fetching old version on my machine

[DavidTheExplorer]

I'm not a maintainer, but why does the library need to switch to gradle?

[chickeneer]

I'm not a maintainer, but why does the library need to switch to gradle?

Primary reason is that certain additional modules would be more easily compatible with a gradle project as opposed to maven. ACF as it is now, would not have an immediate benefit from said migration.

[DavidTheExplorer]

Primary reason is that certain additional modules would be more easily compatible with a gradle project as opposed to maven. ACF as it is now, would not have an immediate benefit from said migration.

Can you elaborate? Creating maven modules is effortless, and I'm not sure what's the meaning of "easily compatible with a gradle project" - Which project and how?