Add a readme and make it appear on pypi.python.org

The python-jenkins page (https://pypi.python.org/pypi/python-jenkins)
is pretty bare.  This change attempts add info to that page.

Change-Id: I90cc12ba337e2e7e52b4ce0f25204c75faff0f22
fix auth with long username or password

Our auth_headers() helper uses base64.encodestring() which inserts
newlines to generate a nicely formatted text. That is surely helpful for
display purposes but unwanted when forging an authentication string.

encodestring() always append a newline, which was the reason for the
[:-1] slicing.

Switch to base64.b64encoding() and add a test ensuring no newline is
inserted.

Closes-Bug: 1039307
Change-Id: I71c3e6d504a500a1f21ff89b1d54a155da1aaf0e
Merge "fix auth with long username or password"
Yield HTTPError reason on open error

Having only the error code from urllib is not that interesting.
HTTPError inherits from URLError which has a 'msg' attribute.  Output it
along the error code.

HTTPError does not have a 'reason' attribute although python six
provides it for py27 and later. So fallback to 'msg'.

Change-Id: I591684785fd7af43b833e84fa1e40f46a852bef2
Merge "Yield HTTPError reason on open error"