Add .cookbooks to .gitignore

Change-Id: I8bee67cdc3b95ae06efff371e56bdd7fc58e7f5b
Add the ability to install a remote certificate

Currently the dashboard cookbook installs a self-signed certificate from
the cookbook files. This patch adds the ability to install a production
certificate, with its corresponding key, from a remote location.

Change-Id: I0416bbfdc9713ddfebfdfe668e28acc7c6870c21
Implements: blueprint remote-certificate
Added/checked template tests

Change-Id: I23628a45fe41f38ab3d8d9ac312bb82d3973490c
Closes-Bug: #1312172