Help ansible-pull work better in bootstap environment

Add option to specify inventory.  No default is defined since
ansible-playbook already does this and it allows an ansible.cfg in the
git repository to take precedence.
Overall, this should help ansible-pull work with less setup in advance,
which should be helpful in kickstart scenarios.  Much of this was
discussed in issue ansible#2464.

bin/ansible-pull

@@ -44,6 +44,8 @@ import datetime
 import socket
 from optparse import OptionParser
 
+import ansible.constants as C
+
 DEFAULT_PLAYBOOK = 'local.yml'
 PLAYBOOK_ERRORS = { 1: 'File does not exist',
                     2: 'File is not readable' }
@@ -102,6 +104,8 @@ def main(args):
     parser.add_option('-C', '--checkout', dest='checkout',
                       default="HEAD",
                       help='Branch/Tag/Commit to checkout.  Defaults to HEAD.')
+    parser.add_option('-i', '--inventory-file', dest='inventory',
+                      help="specify inventory host file")
     options, args = parser.parse_args(args)
 
     if not options.dest:
@@ -115,9 +119,12 @@ def main(args):
     now = datetime.datetime.now()
     print >>sys.stderr, now.strftime("Starting ansible-pull at %F %T")
 
+    inv_opts = 'localhost,'
     limit_opts = 'localhost:%s:127.0.0.1' % socket.getfqdn()
     git_opts = "repo=%s dest=%s version=%s" % (options.url, options.dest, options.checkout)
-    cmd = 'ansible all -c local --limit "%s" -m git -a "%s"' % (limit_opts, git_opts)
+    cmd = 'ansible all -c local -i "%s" --limit "%s" -m git -a "%s"' % (
+            inv_opts, limit_opts, git_opts
+            )
     rc = _run(cmd)
     if rc != 0:
         return rc
@@ -129,6 +136,8 @@ def main(args):
         return 1
 
     cmd = 'ansible-playbook -c local --limit "%s" %s' % (limit_opts, playbook)
+    if options.inventory:
+        cmd += ' -i "%s"' % options.inventory
     os.chdir(options.dest)
     rc = _run(cmd)