Feature/fixup

[bradyzp]

Minor quality-of-life improvements in the project and tests.

• Fix the trajectory ingestor leap_seconds invocation in load_trajectory, it was raising an exception because leap_seconds does not accept positional arguments.
• Update the coveralls badge, the path was incorrectly pointing to an old branch coverage report.
• Added a conditional skip to the timesync test suite, these tests can take a while and it's nice to disable them during development. Environment variable must be explicitly set for "develop", so everything will still run by default on CI.

[coveralls]

Pull Request Test Coverage Report for Build 342

• 0 of 1 (0.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 70.949%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
dgp/lib/trajectory_ingestor.py	0	1	0.0%
<!--	Total:	0	1	0.0%	-->

Totals
Change from base Build 340:	0.0%
Covered Lines:	2685
Relevant Lines:	3650

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💛 - Coveralls