load balancer acceptance specs

This provides acceptances tests for ELB Load Balancer and resolves
CLOUD-43, CLOUD-44, CLOUD-45, CLOUD-46, and CLOUD-48.

This is pretty much the same that @garethr did in GH-18 and supersedes
that work.
(refactor) rename Ec2Helper to AwsHelper
(refactor) use get_* instead of find_*

This matches better with the naming convention established with the plural of
the same in the AwsHelper.
(refactor) AwsHelper member client -> ec2_client

 - Simple rename given there is now a client for EC2 and a client for
   ELB as part of the AwsHelper class
(refactor) tag difference checking to AWSHelper

 - has_matching_tags was used in a couple of locations and made more
   sense to move to a standardized location since many AWS resources can
   have tag sets which can be compared
Merge branch 'ticket/master/CLOUD-43-load_balancer_specs'

* ticket/master/CLOUD-43-load_balancer_specs:
  (refactor) tag difference checking to AWSHelper
  (refactor) AwsHelper member client -> ec2_client
  (refactor) use get_* instead of find_*
  (refactor) rename Ec2Helper to AwsHelper
  load balancer acceptance specs

closes #18, closes #39