Revert 'presentation' dir to 0.81 code, add 'presentation2' for 0.9

This fixes an issue where recordings copied from a 0.81 server might
not play back correctly on a 0.9 server.

This changes the 0.9 recording scripts to use playback support files
from a different subdirectory, 'presentation2', while existing 0.81
recordings continue to use the 'presentation' directory.

If the raw files from an old recording are reprocessed, it will
switch to using the newer playback support files.
Use the directory presentation/0.9.0 instead of presentation2

This makes it a bit more obvious how the versioning can work going
forwards, and makes it so that we do not need to update the nginx
config each time we have a new version of the playback files.

The 0.81 files remain at the top level of the presentation directory
for compatibility reasons.
Move 0.81 files to a subdir, add nginx redirect for them.

Now the 0.81 presentation playback files are in an appropriate versioned
directory. If desired, the recording metadata can be updated to reference
the versioned files directly, but an nginx redirect has been added so
that unmodified recordings will also work.
Add a note to the nginx config to tell 0.9.0 beta users of a possible upgrade path
added a check to make sure that ICE negotiation has finished before showing that the call has been accepted in the UI
Merge pull request #416 from SenecaCDOT-BigBlueButton/add-ICE-improvement

Update to ICE handling
Changed the wording of the webrtc messages to make them easier to understand
Merge pull request #418 from SenecaCDOT-BigBlueButton/webrtc-string-change

Changed the wording of the webrtc messages to make them easier to understand
a few tweaks on the client check page: build.xml downloads the image for the download speed test, config doesn't have someone's IP address (just like a config.xml.template), securityError on port check doesn't throw an exception anymore
added a SDP hack for Firefox to replace the 0.0.0.0 in the c line
Merge pull request #419 from SenecaCDOT-BigBlueButton/mangle-firefox-sdp-c

Added a SDP hack for Firefox to replace the 0.0.0.0 in the c line
 - put sending of rtp packet to fs in another thread
implemented the policy request on deskshare service, to support check on port 9123 by the client checker
Reenable the LayoutChangeEvent
added translation of the default layout definitions
cleanup; using a config.xml template, and added some logic in the build.xml to set config.xml with the proper host IP
Bugfix: removing event listeners and closing netconnections
changed two of the layout names
Merge branch 'improving-client-checks' of https://github.com/mconf/bigbluebutton into improving-client-checks
updated the mobile demo to work with the upcoming BBB AIR Mobile app