- Using same clang format file for old and new files.
- Moving out all TextSecure code to allow other clients (OS X, iOS) to
integrate easily TextSecure functionality.
- Use TextSecure API to signup.
• rejects unhandled media with unsupported attachment message
• for supported media, handling of MIME type/file extension conversion in a single place
• groundwork for future handling of additional types via e.g. conversion