Needed for java 9 support.

This fixes issues downloading from dmdirc.com over SSL, as
previous versions of gradle didn't support SNI.

Add a new task that actually downloads dependencies by
forcing them to be resolved. Make circle use that.

This makes incremental build time ~2.5s on my machine.

Clover doesn't currently work due to a bug in lambda handling,
and we can't disable that with the plugin. Clover 4.0.3 should
fix this.

Seems to be fairly common layout, and gets them out of the root.

`./gradlew clean cloverAggregateReport` in meta will create a new
report for all the projects with tests.

Plugins that don't have any tests won't show up at all.

This changes any com.dmdirc.* dependency references into
local project references.

It doesn't yet work for the parser as that's a different
group, and doesn't have independent projects.