Collect basic diagnostics in response to USR1

Capture:
 * Current contents of /varz
 * Information about pending requests, including
   - Request ID
   - Requested URI
   - Traceback

The diagnostic information will be written to a file in the configured
'diagnostics' directory or into a temporary directory if not configured.
Expose configuration for diagnostic output directory

* Generate `directories` configuration in the cc config documents
* Update api control script to create diagnostics directory with the
  appropriate owner
Merge remote-tracking branch 'origin/pr/227' into HEAD
Merge remote-tracking branch 'origin/pr/229' into HEAD

Signed-off-by: Joseph Palermo <jpalermo@pivotallabs.com>

Conflicts:
	bosh-templates/cloud_controller_api.yml.erb
	bosh-templates/cloud_controller_clock.yml.erb
	bosh-templates/cloud_controller_worker.yml.erb