mysql_variables: fix inconsistent params, fixes ubuntu 16.04 support

In the mysql_user module, login_host is defined as "localhost". Setting this to localhost also fixes Ubuntu 16.04 support.

To make it more consistent in the future, the params in all mysql modules should move to module utils. I'll take care.

Also fixed a few other things along.

database/mysql/mysql_variables.py

@@ -51,7 +51,6 @@ EXAMPLES = '''
 '''
 
 
-import os
 import warnings
 from re import match
 
@@ -118,9 +117,9 @@ def main():
     module = AnsibleModule(
             argument_spec = dict(
             login_user=dict(default=None),
-            login_password=dict(default=None),
-            login_host=dict(default="127.0.0.1"),
-            login_port=dict(default="3306", type='int'),
+            login_password=dict(default=None, no_log=True),
+            login_host=dict(default="localhost"),
+            login_port=dict(default=3306, type='int'),
             login_unix_socket=dict(default=None),
             variable=dict(default=None),
             value=dict(default=None),
@@ -128,19 +127,16 @@ def main():
             ssl_key=dict(default=None),
             ssl_ca=dict(default=None),
             connect_timeout=dict(default=30, type='int'),
-            config_file=dict(default="~/.my.cnf")
+            config_file=dict(default="~/.my.cnf", type="path")
         )
     )
     user = module.params["login_user"]
     password = module.params["login_password"]
-    host = module.params["login_host"]
-    port = module.params["login_port"]
     ssl_cert = module.params["ssl_cert"]
     ssl_key = module.params["ssl_key"]
     ssl_ca = module.params["ssl_ca"]
     connect_timeout = module.params['connect_timeout']
     config_file = module.params['config_file']
-    config_file = os.path.expanduser(os.path.expandvars(config_file))
     db = 'mysql'
 
     mysqlvar = module.params["variable"]
@@ -187,4 +183,5 @@ def main():
 from ansible.module_utils.basic import *
 from ansible.module_utils.database import *
 from ansible.module_utils.mysql import *
-main()
+if __name__ == '__main__':
+    main()