WIP: add dynamic configuration http endpoint and cmdline arguments

It is able to add and remove node now!

goal:
- [x] add add/remove http endpoint
- [x] add add/remove command line
- [x] run smoothly after join
- [ ] save/load info from store - waiting on cluster store

non-goal:
- exit when removed
- add replace feature
- check for add existing node or remove nonexistent node