uWSGI apps should place sockets in /run/uwsgi

/var/run/{gdash,graphite-web} are wiped on boot and not recreated until Puppet
has had a chance to run, causing the services to fail to start. Instead, gdash
and graphite-web should place their sockets in /run/uwsgi, the creation of
which is ensured by the uwsgi master init Upstart job.

Change-Id: I2846330f7ca3438ae2d73448a5cdfccb6179f653