Multi instance

[M5oul]

• [x] https://github.com/duniter/duniter_ynh/commit/3ecb69de8f431383a7e87a1deb30fcc30cf918ad
• [ ] use duniter_default database name for first instance to facilitate CLI manipulation.
• [ ] handle database name and path with --mdb $app option with every duniter command.
• [ ] handle upgrade from duniter_default database to duniter__1, duniter__2…etc
• [ ] install: needs helpers to check if debian package is installed to not install two times
• [ ] remove: remove debian package only if it's the last duniter installed app. (need to develop helper)
• [ ] upgrade:
  • upgrade of duniter package for all running instances
  • restart all running instances
• [ ] manifest: set the app multi_instances.

[M5oul]

Should be possible using different Unix users to be able to run separates daemons. Considering the port management, it depends if BMA is enable and WS2P public enabled. WS2P private does not need a port to work.