Implement on boarding process

**Detailed Description**
Demos currently start with a fixed set of participants

**Actual Behavior**
Demo (AppNet) participants are a known list in advance with values for private/public and encryption keys set in configuration files.

**Expected Behavior**
It should be possible for a new appnet participant to join the network and optionally share keys with parties the participant is likely to exchange messages with.

**Environment:**
- Java: [e.g. OpenJDK 11.0.4]
- Node: [e.g. v12.9.1-x86]
- OS: [e.g. Ubuntu 18.04]
- Version: [e.g. 1.0.1]

**Additional Context**
Add any other context about the problem here. Attach any logs here, if applicable.