Batch mode

[HannaLindgren]

Open a list of audio files and batch run them through the Chrome dictator.

• [x] Find a solution for running a background process to run the recogniser outside of the browser
• [x] Implement API call to run the recogniser on the server side for existing audio files
• [ ] Implement a single API call to both send audio and run recogniser on the server side
• [ ] Create a separate client application page for the batch mode