Fixed pythonic variable instantiation to be correctly created in the int...

...ialization of the object.  The previous code did not work as the variables did not exist and were resolving to nil.  I have tested this and it is working against our current zabbix 2.0.x server.

This also fixes the previous complaint about the instance variable for custom_headers and the other variables.  Like the previous user mentioned, instance variables cannot be defined in this manner.  

The latter fixes were with spacing.