Add database command to remove dataruns

[bcyphers]

Right now, if you create a datarun with a typo or just decide you don't want to run it, there's no simple way to remove it from the database. We should add it as a subcommand to enter_data.py. Maybe:

python enter_data.py remove --datarun 1

likewise,

python enter_data.py remove --dataset 1

[bcyphers]

Actually, there should be two different functions:

1. one to delete a dataset or datarun and all associated data from the database, and
2. one to finish a datarun prematurely, keeping its data but preventing worker.py from discovering it.

[jtanman]

Would it also be possible to add a way to continue a data run with a higher budget? For example running more iterations of a certain method that looked promising but using previous information about parameters or just wanting to continue searching.

[bcyphers]

@jtanman great suggestion. Yes, we can totally add that.

More generally, there should be an API in database.py for amending/updating datarun info.

[jtanman]

Awesome! Thanks a ton for the work on this by the way. I've been starting to use it, and it saves so much time!

[micahjsmith]

This should be addressed by #82 and can be closed if so.

[beevabeeva]

Doesn't look like this was implemented. Definitely wasn't updated in docs (as far as I can tell). This feature is actually essential for developers trying to implement custom classifiers, because testing becomes almost impossible when we have to manually kill ATM.

Edit: To those facing the same problem I get around it by deleting atm.db. This removes all previously created/halted dataruns.