web, client: only automatically start call if incoming message contains sdp or candidate
Android: added a webview based example application
Android: added a native example application which shows a self-view
channel_server: convert SDPs and candidates to JSON and vice versa
channel_server: parse/generate candidates without relying on parse/generateCandidate in sdp.js
channel_server: no longer delete translated session/candidateDescriptions
channel_server: warn if sdp.js is missing, but don't crash