Use the latest rendering engine available

So that IE is aware of media queries

Fixes dw-free#836
Merge pull request #71 from afuna/turn-off-ie9-compatibility-mode-bug-836

Use the latest rendering engine available
[#843] Add "status: claimed" when someone claims an issue

There's no push notification for when someone does it using the
dropdown, but this will work for most people because most people can't
select from a dropdown anyway
Add response text for easier debugging

(can be viewed in Github -> Settings -> Hooks -> your webhook -> Recent
Deliveries -> Response)
[#843] Add status: unclaimed / status: claimed automatically

* only to type: issue, not type: pull request

* when the issue is opened, apply the claimed/unclaimed status

* when a comment is made on an issue, update the claimed/unclaimed status
  if it's been changed without our noticing (may have been selected via
  the dropdown, for example), and make sure to automatically add the
  claimed/unclaimed status if the labels have been edited
[#843] Assign / add status: claimed when someone makes a pull request

Includes some refactoring of common functionality into a function
Merge pull request #72 from afuna/github-claim-labels-bug-843

Automate status: claimed/status: unclaimed
Add medium/large_media_query, and image handling

For dreamwidth/dw-free#841 and dreamwidth/dw-free#838
Merge pull request #73 from afuna/medium_large_media_query

Add medium/large_media_query, and image handling
[#74] Only assign to someone saying "claim" if bug is not already claimed
[#74] Get rid of type: pull request, type: issue
[#74] Remove status: unclaimed tag; keep status: claimed
Merge pull request #75 from afuna/labels-claiming-tweak-bug-74

Adjust labels / claiming for Github Issues redesign
Merge branch 'release-1.21' into develop

* release-1.21:
  [#74] Remove status: unclaimed tag; keep status: claimed
  [#74] Get rid of type: pull request, type: issue
  [#74] Only assign to someone saying "claim" if bug is not already claimed
  Add medium/large_media_query, and image handling
  [#843] Assign / add status: claimed when someone makes a pull request
  [#843] Add status: unclaimed / status: claimed automatically
  Add response text for easier debugging
  [#843] Add "status: claimed" when someone claims an issue
  Use the latest rendering engine available