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.
- Modified data type for port definition from string to integer
- Modified login_host default value for compatibilize with port definition according with MySQL Documentation (https://dev.mysql.com/doc/refman/5.0/en/connecting.html)
Docs imply the mysql_variables is used to operate a single variable therefore
- fail before making any db connections if variable is not set
- validate chars for mysql variable name with re.match(^[a-z0-9_]+)
- use "SHOW VARIABLE WHERE Variable_name" instead of LIKE search
- getvariable() returns only the value or None if variable is not found
- the module returns only the found variable value instead of tuple for easier operation eg. as registere variable in tasks
