Include '/' & '.' when password_hash generates a new salt

The password_hash filter will generate a salt value if none is supplied.
The character set used by Ansible

(upper & lowercase letters, digits)

did not match that used by libc crypt

(upper & lowercase letters, digits, full stop, forward slash).

This resulted in a slightly smaller key space, and hence hashes would be
slightly easier to attack (e.g. by dictionary, brute force).

lib/ansible/plugins/filter/core.py

@@ -256,7 +256,8 @@ def get_encrypted_password(password, hashtype='sha512', salt=None):
                 saltsize = 8
             else:
                 saltsize = 16
-            salt = ''.join([r.choice(string.ascii_letters + string.digits) for _ in range(saltsize)])
+            saltcharset = string.ascii_letters + string.digits + '/.'
+            salt = ''.join([r.choice(saltcharset) for _ in range(saltsize)])
 
         if not HAS_PASSLIB:
             if sys.platform.startswith('darwin'):