Admin creds instead of primary and alt in swift tests

Change-Id: I7a25df68a9f2a3401c09215cc3286a7ab95a526f
test_access_public_container_object_without_using_creds skipped

Change-Id: I5fea5f4415a1f95183d958a8ebe6c5d759ccc8c4
test_versioned_container skipped

Change-Id: I2ffbea55382f702684e73c43f79b9aaeadbf456c
text-html type is absent in TXT_ENC

If we get response with 404 status code and this response
contains in headers "content-type: text/html", NotFound
exception isn't raised.
Add 'text/html' type of content and convert value of
this parameter to lower case.

Change-Id: I632701f43219fa6c0efc6e95bf6007cb0a3ff0c2
Closes-Bug: #1269712