Embed Dropbox images

We need to pass a parameter, "?dl=1", to get the actual file
Check GET parameters in image embedding

This is a great candidate for the tests!
Don't watch for changes on existing lines

How did we miss this angular 1.3 feature? 
It appears to be a bit similar to bindonce, but also works in ng-repeat!

See https://docs.angularjs.org/guide/expression#one-time-binding
Wrap inlinecolour filter in $sce.trustAsHtml

This is required because bo-html is unsafe whereas ng-bind-html requires
"safe" HTML (ng-bind-html-unsafe is deprecated since 1.2)
Remove bindonce for Angular 1.3 One-Time Bindings
Merge pull request #414 from glowing-bear/plugin-fixes

Image plugin fixes
Merge pull request #418 from glowing-bear/kill-the-watchers

[PLS TEST] Don't watch for changes on existing lines, s/bindonce/angular one-time binding/
Delete bindonce file and mention in README
Delete bindonce mention from README

Actually stage the change this time m(
Potential improvements to our README
Merge pull request #400 from glowing-bear/docs

Potential improvements to our README
update angularjs to 1.3 beta 19 to fix bug with quotes around URL
Merge pull request #422 from glowing-bear/update-angular

update angularjs to 1.3 beta 19 to fix bug with quotes around URL
Correct setId placement

The setId had been implemented once on the protocol instance and once
as a (unused) static method.
Make it easier to switch protocols

This commit introduces a new module to switch the protocol. It will
look at a protocol=xxx query parameter (like the debug mode) to do so
teddy support
make teddy default protocol
add challengeauth