Refactor uploads via CLI

[polyatail]

This PR addresses #105, #108, and #109 by:

• Removing FASTX validation code and deleting inline_validator.py
• No longer distinguishing between small and large uploads--all go through same code path
• Continue to interleave FASTX files when paired via FASTXInterleave object
• FASTXInterleave decompresses when necessary, interleaves, and uploads uncompressed
• Upload single-ended files via FASTXPassthru which leaves files as-is
• Switch filter_reads.py to skbio.io FASTX parser, having removed our own parsers

In addition, these changes were made:

• Progress bar during upload now uses click.progressbar
• Errors in multithreaded upload are printed as they happen rather than at the end
• Passing -v sets loglevel to DEBUG rather than INFO
• pytest upgraded to 3.3.0
• Tests using old make_creds_file() were switched over to mocked_creds_file fixture

[boydgreenfield]

I think this is our checklist of TODOs before removing the validation code:

• Add a retry_url or similar param in cases where our proxy fails with a 500 (which will not have quite as good uptime as S3, hard as we try)
• Add a hook to call /samples/<id>/cancel_upload when we cancel a pending upload
• Fix any remaining proxy edge cases that may be blocking (see our internal proxy repo)

[coveralls]

Coverage decreased (-0.3%) to 83.858% when pulling a1495a9 on roo-upload into 7edf4b2 on master.