wsgi testsuite: pep8 and testcase helpers
compat testsuite: testcase helpers
datastructures testsuite: proper asserts
debug testsuite: proper asserts
file -> open
test testsuite: proper asserts
Merge pull request #306 from DasIch/file-removal

file -> open
Merge pull request #305 from passy/asserts

Asserts
get rid of Headers.linked
restrict value of Headers to be unicode
Values of Headers.to_list() should be bytes in py2, str in py3
Use string_types instead of basestring
Use 'as' in except clauses
Use six's xrange
s/file()/open()
Do not try to decode str in py3
Use iter[values,items] from compat
More string/bytes related fixes
add a section in tox.ini to have py.test find the tests
Merge pull request #309 from ThiefMaster/py3-fixes

Various Py3 fixes