Add web application exposing Control Interface over web. All of SET, GET
and TRAP are fully supported.
Notice: TRAP is converted into 'Server-sent events' according to RFC
6202, see also https://www.w3.org/TR/eventsource/ - this requires
corresponding client.
Due to use of special prefix modified version of python
eventsource-client is necessary ATM.
Change-Id: I87d40c80061f8b3d02d656ab8cadabbfb871b461
Related: OS#1646
