Investigate Using Drone CI instead of Travis

[sedouard]

Drone CI follows the same pattern as Travis CI except its easily deployable to any IaaS. Hosting our own Drone CI would help solve a couple problems:

• We could run a bit more secure by running the server only on a privately accessible endpoint
• Virtual unlimited build minutes so long running templates ::cough cough:: sharepoint can finish

We would need to figure out how to run dokku with a private dns but shouldn't be that hard.