Use --schema-base-dir setting of ./Build test for all tests

so instead of
PERL5LIB="$SCHEMA_LOCATION/lib" ./Build test --schema-base-dir=$SCHEMA_LOCATION
it should now be possible to just do
./Build test --schema-base-dir=$SCHEMA_LOCATION
Option to start a custom mysql for ./Build test

Mantis: 3435#c23805
Use a mysql dump instead of a mysql data directory for tests

Mantis 3435#c23805 (still)