Fix for various PEP8 errors.

pep8 1.5.2 started to report errors when a new line follows the
parameter equal, and when a variable is redefined in a list
comprehension.

Signed-off-by: Tomaz Muraus <tomaz@apache.org>
Allow user to pass ex_ebs_optimized argument to the create_node method
in the EC2 driver.

Closes #272
Update CHANGES.
Update EC2 instance and pricing information.

Closes #256
Update tox lint step to also verify syntax in the pricing.json file.
Fix broken test.
Fix lint.
Updating the pricing information to match new AWS pricing changes effective April 1st, 2014

Signed-off-by: Tomaz Muraus <tomaz@apache.org>
Add script for scraping and updating EC2 pricing data.
Update EC2 instance and pricing information.
Remove print, fix pricing file.
Add new r3 instance types to the EC2 driver.