Changed the HTTP connectivity from urllib to httlib

This enables persistent http connections (Keep-Alive) and is hence
slightly faster. Especially if you are behind a chain of web proxies and
update a lot of cells.
Removed the close() for HttpSessions.

The method was broken, not used & not tested. The sessions should be
closed when the process terminates anyways. If you need a close, because
you are running this inside of some container, it is easy enough to
iterate through the connections and close them all.
updated examples
fixed typo
Update README.md
Formatting update
Fixing #35 and rest bytes byte incompatibilities
changed index layout
Fixed update_cells error in Python 2.7 #43
version bump
Adding documentation about two factor authorization.
Merge pull request #46 from commadelimited/two-factor-auth-update

Adding documentation about two factor authorization.
Update README.md
Update README.md
Added support for removing worksheets from a spreadsheet.
removed a forgotten print statement
Merge pull request #48 from aginor/master

Adding support for removing worksheets
Fixed #49
Added Andreas (aginor) to the contributors list
Added create and delete worksheet examples