Fix HTMLParser related deprecation warnings in Py3.4
Patch docutils.io.FileInput to not use "U" mode in py3

"U" mode is redundant in py3 since "newline" argument replaces it and by default
universal newlines is enabled. As of py3.4, "U" mode triggers a deprecation warning.
Merge pull request #1380 from avaris/py34_warnings

Fix for Python 3.4 deprecation warnings while running tests