remove more references to runtests.sh
PY3 MimeTypes wants files in text mode.

See http://hg.python.org/cpython/file/2766320bdb10/Lib/mimetypes.py#l202

before: 455 failed, 248 passed, 10 skipped, 8 warnings, 55 error in 88.36 seconds
after:  466 failed, 253 passed, 12 skipped, 8 warnings, 49 error in 90.15 seconds
normalize header values to bytes
fix ftp test cases
PY3: port scrapy/utils/conf.py
PY3: port scrapy/utils/gz.py
PY3: port scrapy/utils/httpobj.py
lint scrapy/http/request/*.py
Merge pull request #828 from dangra/string-headers

normalize header values to bytes (and PY3)
PY3 enable more tests
PY3 fix test_utils_sitemap.

Sitemap class is only initialized with bytes by Scrapy;
broken tests was only a testing issue.
PY3 port scrapy.utils.spider
PY3 enable more tests
PY3 port scrapy.utils.misc.arg_to_iter; fix scrapy.utils.misc.md5sum doctest
TST enable doctests for Python 3
PY3 port scrapy.contrib.feedexport
optparse to argparse