improve svg

[andreineculau]

http://for-get.github.io/http-decision-diagram/httpdd.fsm.html

• keep/switch from jointjs
• elements should be read-only
• view should be scalable
• view should be closer (visually) to the PNG version
• elements should have a popover
• ...
• go wild, and disobey all the above!

PS: have a look at https://github.com/for-GET/http-decision-diagram/blob/master/httpdd.fsm.html.coffee to see some of the obscure workaround/assumptions when processing the JSON file