Logging

[hexylena]

I booted up a new galaxy and found the UX of getting IEs unpleasant, so...

• enhanced error message if you're running on localhost, now it's obvious that you've bound galaxy to 127.0.0.1 and it isn't going to answer docker questions.

Enhanced dev experience:

• exporting DEBUG=True (or `true) now sets the logging level in galaxy.py
• logging includes many useful things like what URLs are being contacted, etc.

Other modifications:

• completely deprecated the conf stuff, replacing all with os.environ queries.
• history_id as passed on the cli is used in get_galaxy_connection, if applicable. I imagine a None value there might've been causing issues.

[hexylena]

Sorry for duplicate commits, rebased.

[bgruening]

looks good now, thanks!