Automatically execute objects when telescope is available

[rprechelt]

Once the executor is finished calibrating, it needs to query the Google Calendar API to check whether anyone has the telescope scheduled. If the telescope is completely available, the telescope should automatically complete observations.

Needed features:

• [x] When creating an observation in the web app, a user needs a tickbox to disable automatic completion (in case they are trying to take objects at particular times throughout the month)
• [x] Method to query Google Calendar API from the atlas server and decide whether to automatically observe
• [x] How do we pick the order of objects? Do we sort by submit age, by quality, or some factor of the two? This needs to be decided. Thoughts?

[rprechelt]

This has been implemented; Executor queries the Google Calendar API to see if the telescope is booked, if not, it loads the General program from all the users and attempts to execute that.