Compilation of Quick Features

Running thru all of the TODOs that we've been marking as we completed other tasks...
- Figure out progression bar (SCRAPPED)
- [ ] Fix proper blockchain update command
- [ ] Add db types to `connect_to_db()`
- [ ] If training process is in-progress, do not allow another call to `/start-training`
- [x] If training process is in-progress, do not allow another call to `/continue-training`
- [ ] Add another endpoint to manually stop training process
- [ ] Fix "rare" bug (line 333 in `aggregator_server.py` - "when training two different models and both are in-progress, one of them may stop when `update_minParams` endpoint is called...or if a node is added mid-way...not sure" - only occurred once)
- [ ] Update `direct_inference()` in `node_server.py`
- [x] Make pathing for init-commands be easier for the user (?)
- [ ] new line after curl response
- [ ] allow MNIST direct-inference input to accept raw image data
- [x] Add a message at the end of a training process (via logger) to indicate the training has finished
- [x] check that module_path exists (if not, don't initialize)
- [x] node checked to see if actually initialized (shows success even if off)