Added check in bbb-conf to ensure beans.presentationService.defaultUploadedPresentation URL is reachable

Update bigbluebutton-client/locale/ne_NE/bbbResources.properties

First implementation of playback of all presentation events (slides, mouse, pan/zoom, and whiteboard)

Added a text file for tracking release.  This will be placed in /etc/bigbluebutton/bigbluebutton-release

fixing the issue reported by a community member on this post: https://groups.google.com/forum/#!msg/bigbluebutton-dev/WgqfuXgPolE/YBAqw7kc0PoJ

implemented multiple definitions layout, so the admin may define specific layouts depending on the role of the participant (see the layout definition)

start to develop an order manager, which would keep track of the z-order of the windows in the canvas

 - update version to 0.8

making components consistent with the user's role: if the user is a participant, he won't see the control buttons (add, save, load), the lock button will be always disabled and the layouts combo will be enable only when the layouts aren't locked

added an attribute to the layout module to show or hide the module control buttons (add, save and load)

it still needs some refactoring, but it's working fine; this is the client side of the layout module which interacts with the server in order to (un)lock the windows layout

first version of the server side layout module - it allows users to lock and unlock the current layout; the layout is defined as a String, which should be a XML String but may be anything, this way is much easy to extend the layout management, since it won't need to change the server code