Making a basic javascript API for the toolbar.
Updating JS api documentation.

Removed parameters to show_toolbar and hide_toolbar.
Removed extra whitespace and added a tab after a long param description.
Fixed copy-paste error for method summary for djdt.cookie.set
Merge pull request #619 from tim-schilling/javascript-api-484

Add a JavaScript API. Fix #484.
Keep the toolbar handle pinned to the side after drag event.

Current behaviour: after handle is moved when the window width is resized the handled keeps its absolute position rather than sticking to the right side of the window. Handle position returns to normal on page reload.
Don't suggest adding the app config to INSTALLED_APPS.

This is more in line with Django's contrib apps.

Fix #621.
Make note of the incompatability with the GZipMiddleware.