Move more responsibility to common EC2 module

Moved `AWS_REGIONS` into `ec2` module
Created `ec2_connect` method in `ec2` module
Updated modules able to use `ec2_connect` and `AWS_REGIONS`

library/cloud/ec2_vol

@@ -127,15 +127,6 @@ except ImportError:
     print "failed=True msg='boto required for this module'"
     sys.exit(1)
 
-AWS_REGIONS = ['ap-northeast-1',
-               'ap-southeast-1',
-               'ap-southeast-2',
-               'eu-west-1',
-               'sa-east-1',
-               'us-east-1',
-               'us-west-1',
-               'us-west-2']
-
 def main():
     module = AnsibleModule(
         argument_spec = dict(
@@ -151,30 +142,13 @@ def main():
         )
     )
 
-    # def get_ec2_creds(module):
-    #   return ec2_url, ec2_access_key, ec2_secret_key, region
-    ec2_url, aws_access_key, aws_secret_key, region = get_ec2_creds(module)
-
     instance = module.params.get('instance')
     volume_size = module.params.get('volume_size')
     iops = module.params.get('iops')
     device_name = module.params.get('device_name')
     zone = module.params.get('zone')
    
-    # If we have a region specified, connect to its endpoint.
-    if region: 
-        try:
-            ec2 = boto.ec2.connect_to_region(region, aws_access_key_id=aws_access_key, aws_secret_access_key=aws_secret_key)
-        except boto.exception.NoAuthHandlerFound, e:
-            module.fail_json(msg = str(e))
-    # Otherwise, no region so we fallback to the old connection method
-    elif ec2_url:
-        try:
-            ec2 = boto.connect_ec2_endpoint(ec2_url, aws_access_key, aws_secret_key)
-        except boto.exception.NoAuthHandlerFound, e:
-            module.fail_json(msg = str(e))
-    else:
-        module.fail_json(msg="Either region or ec2_url must be specified")
+    ec2 = ec2_connect(module)
 
     # Here we need to get the zone info for the instance. This covers situation where 
     # instance is specified but zone isn't.