Resize the slides to occupy 100% of the space
Removing some class variables in WhiteboardPaperModel

They are variables that store the position and size of slides and now are
store with the slide they are associated with.
Fix the color of shapes drawn in the whiteboard
Fix positioning of shapes in the whiteboard, not 100% yet
Redraw shapes when resizing the HTML5 client

Only redrawing shapes that were loaded when the HTML5 started. Shapes
drawn before are not being saved in the arrays yet and so are not being
redraw when resizing (they disappear).
Add WhiteboardRectModel to clean up WhiteboardPaperModel

First version, there are still things that should be moved from
WhiteboardPaperModel to it.
Round borders for rects and pencil in the HTML5 whiteboard

Makes the drawings more similar to the drawings in the flash client.
Add WhiteboardLineModel to clean up WhiteboardPaperModel

First version, there are still things that should be moved from
WhiteboardPaperModel to it.
Add WhiteboardToolModel as a base for whiteboard tools in HTML5

WhiteboardLineModel and WhiteboardRectModel already inherit from it.
Merge remote-tracking branch 'bigbluebutton/html5-bridge' into html5-resize-slides
HTML5: add ellipse and triangle to whiteboard
HTML5: WhiteboardLineModel working for line and pencil tools
HTML5: rects and ellipses work when drawn backwards

Rects and ellipses would not work if drawn from right to left and/or from
bottom to top, but now they work.
HTML5: small fixes in the whiteboard drawings
HTML5: add text tool to whiteboard
HTML5: more small fixes in the whiteboard drawings
HTML5: add WhiteboardCursorModel, simplify whiteboard paper
HTML5: standard method to create tools in the whiteboard

Shrink the code a bit more.
HTML5: add WhiteboardSlideModel

It stores the slides that are shown in the whiteboard.
HTML5: cleanup/refactor whiteboard paper a bit more

PRESENTATION_SERVER was moved to a better place. It was kind of
hardcoded in the client, now it is passed to the client by the
server, so it can be easily configured in the server if needed in
the future.