Device password setter doesn't work
The Device class includes a setter for the password property with the comment:
"Change the authentication password value.  This is handy in case the calling program needs to attempt different passwords."

However, this setter doesn't work:

```
>>> from jnpr.junos import Device
>>> r0 = Device(host='r0',password='incorrect')
>>> r0._password
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'Device' object has no attribute '_password'
>>> r0._auth_password
'incorrect'
>>> r0.open()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/dist-packages/jnpr/junos/device.py", line 414, in open
    raise EzErrors.ConnectAuthError(self)
jnpr.junos.exception.ConnectAuthError: ConnectAuthError(r0)
>>> r0.password = 'user123'
>>> r0._password
'user123'
>>> r0._auth_password
'incorrect'
>>> r0.open()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/dist-packages/jnpr/junos/device.py", line 414, in open
    raise EzErrors.ConnectAuthError(self)
jnpr.junos.exception.ConnectAuthError: ConnectAuthError(r0)
```

It ends up setting the self._password attribute when it should have set the self._auth_password attribute.

diff --git a/lib/jnpr/junos/device.py b/lib/jnpr/junos/device.py
index e000479a..e63245ab 100644
--- a/lib/jnpr/junos/device.py
+++ b/lib/jnpr/junos/device.py
@@ -129,7 +129,7 @@ class Device(object):
         Change the authentication password value.  This is handy in case
         the calling program needs to attempt different passwords.
         """
-        self._password = value
+        self._auth_password = value
 
     # ------------------------------------------------------------------------
     # property: logfile
diff --git a/tests/unit/test_device.py b/tests/unit/test_device.py
index 79d9a7cd..65734233 100644
--- a/tests/unit/test_device.py
+++ b/tests/unit/test_device.py
@@ -221,7 +221,7 @@ class TestDevice(unittest.TestCase):
 
     def test_device_set_password(self):
         self.dev.password = 'secret'
-        self.assertEqual(self.dev._password, 'secret')
+        self.assertEqual(self.dev._auth_password, 'secret')
 
     def test_device_get_timeout(self):
         self.assertEqual(self.dev.timeout, 30)

['lib/jnpr/junos/device.py', 'tests/unit/test_device.py']