Showing registration status for boot camps on index page
* Merging Trevor King's modifications to boot camp compilation to show open/restricted status.
* Adding optional metadata 'registration' to boot camp pages to show if they are open or restricted.  If metadata not present, boot camp registration hasn't started yet.
* Changing format of boot camp index page accordingly.
Merge branch 'master' of github.com:swcarpentry/website into registration
Fixing build complaints in new boot camp index page
Merge pull request #326 from mikej888/master

Added line to CONTRIBUTING.md about submodules
Merge pull request #325 from gvwilson/master

Modifying the way boot camps are displayed in the index page
Adding another paper to the bibliography
New page for University College London April camp
Updated online office hours page
Fixed typo on office hours page
Merge pull request #327 from amyrbrown/ucl-bootcamp

New page for University College London April camp
Update ubc-swc-r.html

Fixed typo in my name :)
Boot camp page for UMass May 23-24
Merge pull request #329 from amyrbrown/umass-bootcamp

Boot camp page for UMass May 23-24
Two blog posts
Blog post with good/bad feedback from UW Room B (Matt and Doug).

Also includes a couple pictures, one linked in the post.
Fixing typo in Doug's name.
Merge pull request #332 from jiffyclub/uw-feedback-blog

Blog post with good/bad feedback from UW Room B (Matt and Doug)
Added mailing list info/sign up to contributing page, and some clean up.

Specifically, I merged the Report Bugs and Suggest Improvements into the Create
and new Discuss section. I removed stuff about creating new slides and audio
because that's no longer relevant.

Additionally, I added a Discuss section with links to the blog, announcement
mailing list, and the discussion mailing list. There is a form on the page
now that lets people (un)subscribe from the announcement mailing list.
Blog post on teaching with ipythonblocks at UW.