@joeyAghion => Make changes to deploy to artsy sonatype

This makes changes to deploy to the maven repo associated with artsy.

I've already deployed yesterday's changes here: https://oss.sonatype.org/content/repositories/snapshots/com/github/artsy/snowplow-common-enrich_2.10/ (2.10 is the scala version #, 0.2.2 is the library version #)

Followup is to update the scala-common-enrich dependency to this source/version

p.s. Have updated the wiki docs with the plugin install we discovered was required yesterday.