Add base-path parameter to Coveralls

[mitchellolsthoorn]

Coveralls is having trouble parsing the LCOV files generated during the test and coverage scripts. According to this issue, the base-path is necessary next to the path to LCOV to make sense of the data in the LCOV file. This was unclear from the documentation

[coveralls]

Pull Request Test Coverage Report for Build 4197373157

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 0.0%

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Totals
Change from base Build 4195489852:	0.0%
Covered Lines:	0
Relevant Lines:	0

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 4488900916

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+53.9%) to 53.931%

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Totals
Change from base Build 4313025505:	53.9%
Covered Lines:	832
Relevant Lines:	1453

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💛 - Coveralls

[mitchellolsthoorn]

This apparently doesn't fix the problem

[dstallenberg]

Finally coverage.