run integration tests with pytest
added docs to testsuite
_get_shared_image method plus tests
better integration tests
handle multiple images coming from ias
tests for list_images
fixed tests code
Spelling/grammar fix to docstring
iterate through region ditcts non-destructively
Merge pull request #14 from planctechnologies/gns-81

Added two relevant methods to RackspaceCtrl class:

_get_shared_images to perform HTTP requests against gns3-ias server
list_images higher-level method to retrieve a dictionary (image_id, image_name) of shared images ready to be used by the GUI client
A note about integration tests: I've made significant changes to give developers the opportunity to pass rackspace credentials through command line and have more control about which tests to run and how.
More details here: https://planctechnologies.atlassian.net/wiki/display/GNS/Developer+Installation