Support all mount options in vue-test-utils

[dfcook]

Allow all supported options to be passed to vue-test-utils mount function. Replaces #12 , hence including test from that PR in here.

[coveralls]

Pull Request Test Coverage Report for Build 76

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.5%) to 95.455%

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Totals
Change from base Build 70:	0.5%
Covered Lines:	44
Relevant Lines:	45

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💛 - Coveralls

[tim-maguire]

Yeah, this makes loads of sense to me. Much better.

Further down the line, there's probably a decent argument for deprecating the props key..?

[dfcook]

There is, should we bite the bullet and do it here making it a breaking change?

[dfcook]

Pushed a further commit that will allow props or propsData to be passed and will copy props to propsData, this will keep backwards compatibility and allow propsData to be used going forward.

[tim-maguire]

Yeah, this seems like a sensible approach.