Setup script for new events

[bridgetkromhout]

• template changes to be more scriptable
• sample event fixes

This is related to #8 but perhaps covers a bit different ground; instead of starting from hugo new I'm starting from a sample event (content files and yaml).

I'm also removing the proposals.md file entirely since we're no longer doing that.

A sample run:

Bridgets-MacBook-Air:devopsdays-web bridget$ ./make_new_event.sh 
Enter your event year (default: 2016): 
Enter your city name: Silicon Valley
Enter your devopsdays event twitter handle (defaults to devopsdays):@devopsdayssv
Bridgets-MacBook-Air:devopsdays-web bridget$ git status
On branch bridget-new-event-setup
Untracked files:
  (use "git add <file>..." to include in what will be committed)

    content/events/2016-siliconvalley/
    data/events/2016-siliconvalley.yml

nothing added to commit but untracked files present (use "git add" to track)
Bridgets-MacBook-Air:devopsdays-web bridget$ 

[bridgetkromhout]

Since hugo insists on a date, I picked one that's unlikely to appear naturally, so I know what to search/replace on.