bugfix: don't download the package every time

- aphyr.com doesn't seem to support conditional gets
- FIXME: yum package wants that, too.
Fix bug in bugfix (not downlod package all the time)
make rbenv requirement less strict

as there's no specific reason for strictness here
Bump default riemann version

Make default riemann version 0.2.6
Remove some trailing spaces
Add some kitchen dependencies
Use yum-epel instead of yum::epel
Completely revamp riemann cookbook

Rename cookbook 'riemann' instead of 'riemann-server'
Remove runit
Deploy dashboard from a bundle.