1. get rid of the whisper layer and handle everything in the communication layer
2. Create a gethWhisper and a parityWhisper plugin that has the same files as packages/embark/src/lib/modules/geth, except with a whisperClient instead of gethClient, and will include most of https://github.com/embark-framework/embark/blob/master/packages/plugins/whisper/src/index.js.
3. Get rid of any whisper registration in geth.
4. In the whisperGeth and whisperParity plugins, modify the request for communication:node:register, to end up calling `startWhisperNode`