wip on filedrop, default event still fires
removed dropbox image as background on message view
don't get socket.io from cdn anymore for offline development
1st working implementation of sending files through datachannel
save sent files to disk using download link
implemented setter for meta
use a separate reader for each file allowing the file instance to be passed to the callback so we still know the file info when the read operation completes
renamed function so it better describes what it does
Changed implementation of sending files. Now uses readAsFileURL instead
of the apparently deprecated readAsBinaryString.
Sent files are added as a download list on the receiving end.

TODO: change implementation to use ArrayBuffers which should be faster
Meta data of Message cannot be set directly anymore but has an
interface of setMeta that set key/values.