Rename coin agent processes

Rename

• agent --> coin-agent
• bootstrap-agent --> coin-bootstrap-agent
  This will make my life easier with monitoring only processes starting with "coin-", since there are other "agents" like ssh-agent in most systems.

How to roll out this change

1. coin-bootstrap-agent needs to change to request to download coin-agent first, and if the answer was 404 request to download the legacy agent
2. Tier1 images need to rebuilt with the new coin-bootstrap-agent (provided by the new coin-setup)
3. Tier1 images should be rolled out - this should cause zero side-effects, since the running Coin is still the old version with the agent binaries
4. The new Coin can now be installed, providing the new coin-agent binaries
   • (If anything goes wrong, we just revert to the old Coin with agent binaries)
5. Later, we remove the legacy agent download from coin-bootstrap-agent