Changed zf2 version and keywords

Updated the composer to not require latest dev-master for zf2.  If this is to be used in production env's you can't count on the latest and greatest being the composer.lock'ed version.

Cleaned up keywords a little.

This looks like a great app.  I wrote one which did the same thing some time ago but you've done a better and more complete job with this.  I'll be using it as a cornerstone to my db.etree.org rewrite.