Updated to work with Dart 1.24#1

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hoylen wants to merge 5 commits intojamesots:masterfrom

hoylen:crypto-package-update

Commits on Jun 14, 2017

Updated dependency to allow more recent versions of crypto and mockito
hoylen
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Commits on Jun 29, 2017

Commits on Jul 3, 2017

Set version to 0.14.2, since only non-breaking changes made.
hoylen
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