jruby: analytics: use Executors from killbill-concurrent

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
analytics: initial implementation of a dashboard

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
analytics: add first set of system dashboards (payments)

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
analytics: fix queries to look in the past only

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
analytics: fix X axis drawing

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
analytics: add pivoting and filtering support

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
analytics: iteration on current queries

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
analytics: add more useful reports

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
analytics: ensure all graphs share the same X axis

This revisit the normalization code as well, adding zeros for missing
days.

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
analytics: add simple smoothing functions

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
Create README.md
Update README.md
analytics: implement filtering

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
analytics: add invoice and invoice item reports

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>