Additional test for stream availability and mock user input

[pshivraj]

This PR updates Test cases for:

1. Stream availability check.
2. Mock user input for netcdf file downloads.

[coveralls]

Pull Request Test Coverage Report for Build 220

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 23 unchanged lines in 1 file lost coverage.
• Overall coverage remained the same at 75.599%

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Files with Coverage Reduction	New Missed Lines	%
/home/travis/miniconda/envs/TEST/lib/python3.6/site-packages/yodapy/datasources/ooi/init.py	23	80.0%
<!--	Total:	23		-->

Totals
Change from base Build 208:	0.0%
Covered Lines:	663
Relevant Lines:	877

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💛 - Coveralls