rax modules improvements

* Catch issues with invalid regions
* Ensure we send string only data as meta values in the rax module
* Add public_key/lookup example for rax_keypair
* Clean up import statements

library/cloud/rax_queue

@@ -1,4 +1,4 @@
-#!/usr/bin/python -tt
+#!/usr/bin/python
 # This file is part of Ansible
 #
 # Ansible is free software: you can redistribute it and/or modify
@@ -55,15 +55,11 @@ EXAMPLES = '''
       register: my_queue
 '''
 
-import sys
-import os
-
-
 try:
     import pyrax
+    HAS_PYRAX = True
 except ImportError:
-    print("failed=True msg='pyrax is required for this module'")
-    sys.exit(1)
+    HAS_PYRAX = False
 
 
 def cloud_queue(module, state, name):
@@ -76,6 +72,10 @@ def cloud_queue(module, state, name):
     instance = {}
 
     cq = pyrax.queues
+    if not cq:
+        module.fail_json(msg='Failed to instantiate client. This '
+                             'typically indicates an invalid region or an '
+                             'incorrectly capitalized region name.')
 
     for queue in cq.list():
         if name != queue.name:
@@ -126,6 +126,9 @@ def main():
         required_together=rax_required_together()
     )
 
+    if not HAS_PYRAX:
+        module.fail_json(msg='pyrax is required for this module')
+
     name = module.params.get('name')
     state = module.params.get('state')