fix gradle setup and .gitignore

[davidmoten]

Hiya
First pull request being for changes just so I could build and import to IDE.

• No gradlew wrapper present so didn't know which version to use for building. I added 3.5 because it matched the version in gradle-wrapper.properties but happy to use whatever version you dictate.
• ide metadata should not be present (added .classpath, .project, .settings to .gitignore and removed)
• removed gradle metadata (.gradle was present though in .gitignore)

Oh to save you some time perhaps (I know you work across a lot of languages!), to import the project into eclipse:

./gradlew eclipse

and import as eclipse project as usual.

[davidmoten]

Yikes, a major rebase job is needed now. I'll sort it.

[davidmoten]

I've rebased and removed my fixes to test classes, constraining only to setup stuff like gradlew, .gitignore and removing ide metadata etc.

@Cbales can you review this and merge please to avoid more rebase pain?

As part of review what version of gradle do you want to use?

[caitlinrussell]

Thanks so much for the cleanup! I hadn't looked into the included files yet and definitely should have before anyone cloned it. I also did a rebase myself to remove another file, so after we merge this in, you'll want to clone again as well I believe.
The plan right now is to support Gradle 3.5

[davidmoten]

Beaut. git pull on master and no conflicts.