Fix permission error when using local storage for droplets

* Local directory for droplet(without NFS) in CC should be created and chown to vcap
* Nginx config for local root should not be hardcoded
replace hard coded directory
Add Contributing guide
style fixes
Register dea agents with the collector

Signed-off-by: Mike Gehard <mgehard@pivotallabs.com>
Why not include this?

Signed-off-by: Matthew McNew <mmcnew@pivotallabs.com>