add support for vertical-align --> valign attribute
git ignore .coverage
always preserve original css when keep_style_tags=True, fixes: #73, #50, #78
Merge pull request #81 from michi88/upstream

add support for vertical-align --> valign attribute
Merge pull request #83 from michi88/fix_keep_style_tags

always preserve original css
bump version to 2.6.0
all tests in a sub-directory called tests
updated --help example in README
Adding absolute import and Unicode literals from __future__
Switching to absolute_import for Python 3 compatability
Adding Python 3 compatability: mostly with the urllib, some encoiding, a string issue, and a print-statement.
Ugly, but it works: compatibility between the Python 2 and Python 3 argparse.FileType
Using codecs.open to open the version-file with the correct encoding.
Adding the configuration for tox.
Still pondering how to patch this
Moving the tests into their own directory.

--HG--
rename : premailer/test-apple-newsletter.html => premailer/tests/test-apple-newsletter.html
rename : premailer/test-external-links.css => premailer/tests/test-external-links.css
rename : premailer/test-external-styles.css => premailer/tests/test-external-styles.css
rename : premailer/test-issue78.html => premailer/tests/test-issue78.html
rename : premailer/test-unicode.html => premailer/tests/test-unicode.html
rename : premailer/test_premailer.py => premailer/tests/test_premailer.py
Adding Python 3.3 testing with Tox
Confirming that the 50 tests actually do run on CPython (Python 2.7, Python 3.3, and Python 3.4) and PyPy
Fixing the import of StringIO
Switching to BytesIO for binary data, and testing the premailer.premailer.Premailer._load_external_url method