Add credential parameters to the GCE modules.

In order to simplify the workflow with the GCE modules, it's now
possible to add the parameters and project name as arguments to the
various GCE modules.

The inventory plugin also returns the IP of the host in
`ansible_ssh_host` so that you don't have to specify IPs into the
inventory file.

Some update to the documentation are also added.

Closes #5583.

plugins/inventory/gce.py

@@ -73,7 +73,7 @@ Version: 0.0.1
 '''
 
 USER_AGENT_PRODUCT="Ansible-gce_inventory_plugin"
-USER_AGENT_VERSION="v1beta15"
+USER_AGENT_VERSION="v1"
 
 import sys
 import os
@@ -174,6 +174,10 @@ class GceInventory(object):
 
     def node_to_dict(self, inst):
         md = {}
+
+        if inst is None:
+            return {}
+
         if inst.extra['metadata'].has_key('items'):
             for entry in inst.extra['metadata']['items']:
                 md[entry['key']] = entry['value']
@@ -192,12 +196,17 @@ class GceInventory(object):
             'gce_zone': inst.extra['zone'].name,
             'gce_tags': inst.extra['tags'],
             'gce_metadata': md,
-            'gce_network': net
+            'gce_network': net,
+            # Hosts don't have a public name, so we add an IP
+            'ansible_ssh_host': inst.public_ips[0]
         }
 
     def get_instance(self, instance_name):
         '''Gets details about a specific instance '''
-        return self.driver.ex_get_node(instance_name)
+        try:
+            return self.driver.ex_get_node(instance_name)
+        except Exception, e:
+            return None
 
     def group_instances(self):
         '''Group all instances'''