Feature/calendar

Open Tech Calendar is an established hub for tech events in the UK.

All data is fully open through APIs - JSON, ICS, etc - and the project is happy to add more. 

It's also Open Source.

@jarofgreen is happy to chat and work on more Open Data stuff or other features. He, @lewiscowper and I chatted at #mozfest, resulting in this pull request :smile:

P.S. I added a .gitignore file to help stop me checking in its temporary files. Hope that's OK!