Skip tests related to RTMP plugin for Windows

The RTMP plugin is not included in GStreamer for Win32, so the test based on it will fail on Windows.
The workaround is to skip the RTMP test on Windows.
Updates to http errors, and validation

Changed HTTPError class to have more standard error messages, and
custom inner descriptions.

Decoupled JSON Schemas from validate module, now schemas are either
generated by config classes, or stored statically in the api blueprint.

Added JSON validation schemas to recording api Blueprint

Updated validation tests for validate.py changes, changed xunit setups
to pytest fixtures
Freeseer server now broadcasts on host's ip address
Zeroconf support for server
Added licence information
travis dependencies, comments
CLI command to discover Freeseer hosts on this server
Added zeroconf to requirements.txt
Added sleep() workaround for shutdown exception
Changes based on code review
Renamed module from discover to listener
Moved zeroconf logic to frameworks