Oil 98/fix test reset

[ltparis2018]

• new test util function resetOil() to be used within beforeEach() methods in all tests -> resets oil layer initialization
• new test util function setupVendorListSpies() to be used in all tests for features based on the vendor list (uses predefined test specific small vendor list 'fixtures/vendorlist/simple_vendor_list.json')

[coveralls]

Pull Request Test Coverage Report for Build 178

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 8 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.3%) to 24.121%

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Files with Coverage Reduction	New Missed Lines	%
dist/oil.bundle.js	8	24.12%
<!--	Total:	8		-->

Totals
Change from base Build 165:	-0.3%
Covered Lines:	866
Relevant Lines:	2888

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💛 - Coveralls