Revert removal of XcodeCoverage script as part of the build process.

This reverts commit f0c6857af4a2b7dbefbf273199d8a7c1cc56efce.
testDescribeMismatchOfThrowNotExpected
testExceptionMessageCanBeUsedInConjunctionWithStringMatchers
testExceptionWithMessageCanBeUsedInConjunctionWithEqualityMatchers