changed Mysql::dateToApp to return null for "zeroed" mysql dates ("0000-00-00 00:00:00")
Changed Mysql::dateTimeToApp to use the same implementation as Mysql::dateToApp
Added test for dateTimeToApp with zeroed date.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	tests/DataStore/Utility/MysqlTest.php
Merge pull request #2 from ralouphie/master

Changed `Mysql::dateTimeToApp` to work the same as `Mysql::dateToApp`