update to jest: 24.7.1

[6ewis]

After updating we get the following errors/warning that needed a proper fix - thus the updates in the codebase:

 - A "describe" callback must not return a value. Returning a value from "describe" will fail the test in a future version of Jest.

 - A "describe" callback must not return a promise.

 - Trace: The node type SpreadProperty has been renamed to SpreadElement

[coveralls]

Pull Request Test Coverage Report for Build 24

• 10 of 10 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.2%) to 92.308%

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Totals
Change from base Build 16:	0.2%
Covered Lines:	66
Relevant Lines:	68

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💛 - Coveralls