Added October talk and improved architecture using Jekyll capabilities

Hello, 

I have added the October talk from yesterday and I have improved the architecture.

Improvements: 
- Auto archives old talks from the main page
- No duplicated HTML on the main or archived pages
- Decoupled speakers and their bio from talks (enables to update speaker's bio in all the talks by them at once)
- Dynamically creates talk pages with links to Meetup and to the slides where available

I have also added a couple of `template` files to copy paste when adding new talks or speakers. 

I haven't added any new dependencies to the project and I have only used pure Jekyll features. 

I am really bad with design and it could benefit from someone talking a look at the new talks page and maybe improving the links or adding an image for the speaker's twitter profile. 

If you agree with this architecture, I can add dynamic pages for the speakers which dynamically link their talks. 

This PR doesn't depend on the other PR I sent yesterday for adding a simple Vagrant environment. 

@johannac if you like this, I can do a similar thing for the conference one

Thanks, 
- J