preliminary privlege escalation unification + pbrun

- become constants inherit existing sudo/su ones
- become command line options, marked sudo/su as deprecated and moved sudo/su passwords to runas group
- changed method signatures as privlege escalation is collapsed to become
- added tests for su and become, diabled su for lack of support in local.py
- updated playbook,play and task objects to become
- added become to runner
- added whoami test for become/sudo/su
- added home override dir for plugins
- removed useless method from ask pass
- forced become pass to always be string also uses to_bytes
- fixed fakerunner for tests
- corrected reference in synchronize action plugin
- added pfexec (needs testing)
- removed unused sudo/su in runner init
- removed deprecated info
- updated pe tests to allow to run under sudo and not need root
- normalized become options into a funciton to avoid duplication and inconsistencies
- pushed suppored list to connection classs property
- updated all connection plugins to latest 'become' pe

- includes fixes from feedback (including typos)
- added draft docs
- stub of become_exe, leaving for future v2 fixes

test/units/TestSynchronize.py

@@ -18,6 +18,9 @@ class FakeRunner(object):
         self.remote_user = None
         self.private_key_file = None
         self.check = False
+        self.become = False
+        self.become_method = False
+        self.become_user = False
 
     def _execute_module(self, conn, tmp, module_name, args,
         async_jid=None, async_module=None, async_limit=None, inject=None, 
@@ -76,7 +79,7 @@ class TestSynchronize(unittest.TestCase):
         """ verify the synchronize action plugin unsets and then sets sudo """ 
 
         runner = FakeRunner()
-        runner.sudo = True
+        runner.become = True
         runner.remote_user = "root"
         runner.transport = "ssh"
         conn = FakeConn()
@@ -97,7 +100,7 @@ class TestSynchronize(unittest.TestCase):
         assert runner.executed_complex_args == {'dest':'root@el6.lab.net:/tmp/bar',
                                                 'src':'/tmp/foo',
                                                 'rsync_path':'"sudo rsync"'}, "wrong args used"
-        assert runner.sudo == True, "sudo was not reset to True" 
+        assert runner.become == True, "sudo was not reset to True"
 
 
     def test_synchronize_action_local(self):