Rebase attempt

No idea if I'm rebasing properly or not.  This is my first attempt.

library/cloud/cloudformation

@@ -43,10 +43,10 @@ options:
     aliases: []
   region:
     description:
-      - The AWS region the stack will be launched in
+      - The AWS region to use. If not specified then the value of the EC2_REGION environment variable, if any, is used.
     required: true
     default: null
-    aliases: []
+    aliases: ['aws_region', 'ec2_region']
   state:
     description:
       - If state is "present", stack will be created.  If state is "present" and if stack exists and template has changed, it will be updated.
@@ -81,10 +81,24 @@ tasks:
       ClusterSize: 3
 '''
 
-import boto.cloudformation.connection
 import json
 import time
 
+try:
+    import boto.cloudformation.connection
+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']
+
 class Region:
     def __init__(self, region):
         '''connects boto to the region specified in the cloudformation template'''
@@ -146,11 +160,7 @@ def main():
         argument_spec=dict(
             stack_name=dict(required=True),
             template_parameters=dict(required=False),
-            region=dict(required=True,
-                        choices=['ap-northeast-1', 'ap-southeast-1',
-                                 'ap-southeast-2', 'eu-west-1',
-                                 'sa-east-1', 'us-east-1', 'us-west-1',
-                                 'us-west-2']),
+            region=dict(aliases=['aws_region', 'ec2_region'], required=True, choices=AWS_REGIONS),
             state=dict(default='present', choices=['present', 'absent']),
             template=dict(default=None, required=True),
             disable_rollback=dict(default=False)
@@ -159,16 +169,25 @@ def main():
 
     state = module.params['state']
     stack_name = module.params['stack_name']
-    region = Region(module.params['region'])
+    r = module.params['region']
     template_body = open(module.params['template'], 'r').read()
     disable_rollback = module.params['disable_rollback']
     template_parameters = module.params['template_parameters']
 
+    if not r:
+        if 'AWS_REGION' in os.environ:
+            r = os.environ['AWS_REGION']
+        elif 'EC2_REGION' in os.environ:
+            r = os.environ['EC2_REGION']
+    
+    
+
     # convert the template parameters ansible passes into a tuple for boto
     template_parameters_tup = [(k, v) for k, v in template_parameters.items()]
     stack_outputs = {}
 
     try:
+        region = Region(r)
         cfn = boto.cloudformation.connection.CloudFormationConnection(
             region=region)
     except boto.exception.NoAuthHandlerFound, e: