discriminate nginx and direct requests

[sjanssen2]

and either use nginx or tornado file delivery method respectively

I've also added the ability to fetch whole directories from Qiita main. As malicious clients could thus get the WHOLE content of base_data_dir, only directories can be fetched, which are a) listed as "directory" filetypes in Qiita's DB and b) where client provided a valid mountpoint

When Qiita is in testmode, files/dirs can now also be deleted trough an API endpoint, which is not exposed in productive mode.

[coveralls]

Pull Request Test Coverage Report for Build 19296599972

Details

• 182 of 249 (73.09%) changed or added relevant lines in 3 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.2%) to 91.943%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
qiita_pet/handlers/cloud_handlers/tests/test_file_transfer_handlers.py	151	156	96.79%
qiita_pet/handlers/cloud_handlers/file_transfer_handlers.py	28	90	31.11%

Files with Coverage Reduction	New Missed Lines	%
qiita_pet/handlers/cloud_handlers/file_transfer_handlers.py	3	32.33%

Totals
Change from base Build 17326449280:	-0.2%
Covered Lines:	25175
Relevant Lines:	27381

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💛 - Coveralls