Fix :memory: database support for sqlite

[grokloc]

This library doesn't seem to support :memory: databases in sqlite - the fix is simple:

at https://github.com/huntlabs/hunt-database/blob/master/source/hunt/database/driver/sqlite/Connection.d#L78

add something like this:

if (filename == "/:memory:") {
         filename = ":memory:";
}

and now you can use connection strings like sqlite:///:memory

For more info:

https://www.sqlite.org/inmemorydb.html

[zoujiaqing]

Thanks, but we will remove sqlite support in next big release.