add default values to avoid errors from MySQL >= 5.6

see https://blogs.oracle.com/supportingmysql/entry/mysql_server_5_6_default
add default values to avoid errors from MySQL >= 5.6

see https://blogs.oracle.com/supportingmysql/entry/mysql_server_5_6_default
Merge pull request #18 from darkuncle/master

define default values in schema to avoid errors from MySQL >= 5.6