Remove fucking test enumeration from globaleaks.tests.test_submission.
Unicode string are unicode.

Globaleaks test globaleaks.tests.test_submission has
__future__.unicode_literals, therefore there's no need to use u'' to define a
unicode string.
Fix #1023.

Move globaleaks.tests.test_submission.TestSubmission into
globaleaks.tests.handlers.test_submission.
This TestCase acrually tests the handler, so I am moving it inside
globaleaks.tests.handlers package.
Furthermore, I am removing most unused imports in both files.
Note that this commit introduces unicode_literals in
globaleaks.handlers.test_submission and might break something (though not
spotted by any unittest yet).
Remove fucking test enumeration from globaleaks.tests.handlers.test_files.