jsroot: implement raw Text output from THttpServer

1. One could create now 'Text' item on the server side,
   which just disaplyed in the browser.
2. For text display MathJax can be used - one should
   specify 'mathjax' property for Text item.
3. Provide example with Text in httpcontrol.C macro
4. Support 'autozoom' draw option
5. Support _same_ identifier in items list
6. Remove default-ui class from droppable, hide nasty
   effects in StreamerInfo and Text display

Signed-off-by: Bertrand Bellenot <bertrand.bellenot@cern.ch>