Fix test_novnc for python3

When running test_novnc on python3 there are bunch of mismatches between
bytes objects and strings. This commit cleans those up by casting things
where appropriate to ensure everything is the same type on both py2 and
py3. At the same time some sloppy asserts were cleaned up to make the
casting easier.

Depends-On: I349742d80e0abeb7866eeeb647ce18948eff81f8
Change-Id: Ibc95a8e0b264c3df396e866527574cd1aa73611a
1 file changed