Bump release version in sbt build file to 2.2.0-SNAP1.
Added code to deploy scalatest to sonatype.
Make a scalautils sub-project in sbt build, which is an empty project that simply copies over scalautils source files, this project enables scalautils to be deployed as separate jar.
Added project/plugins.sbt to use sbt-pgp sbt plugin.
Added credential settings to project/scalatest.scala, which read username and password from environment variables.
Add OSGI metadata when publishing.
Changed version number to 2.2.0-SNAPSHOT in sbt build.
Added documentation on publishing to sonatype in README.md.
Make GPG file and passphrase to be read from environment variables also.