use the proper container class for strict assert
Merge pull request #350 from mgax/fix-accept-test

use the proper container class for strict assert
fix strict comparison with header (unicode string)
relax requirement on type for content_type
Updated literals
Merge pull request #351 from untitaker/sprint-branch

Updated literals
Merge pull request #352 from mgax/fix-str-types-in-tests

Fix str types in tests