tests: deal with events containing dict in kwargs
tests: deal with events containing dict in kwargs

If kwargs contains dict as one of values, it isn't hashable and can't be
used as value in frozenset/tuple. Convert such values into
frozenset(dict.items()). Only one (more) level is supported, but it
should be enough.

Solution from http://stackoverflow.com/a/13264725

woju/qubes-core-admin,woju/qubes-core-admin,QubesOS/qubes-core-admin,woju/qubes-core-admin,marmarek/qubes-core-admin,woju/qubes-core-admin,QubesOS/qubes-core-admin,marmarek/qubes-core-admin,marmarek/qubes-core-admin,QubesOS/qubes-core-admin