Removed return from 1st line of runDbScript()

Removed return from 1st line of runDbScript()
fixed broken html tag on success page.
handlePost() now will show as many errors as it can (instead of one at a time)
checkPrereqs() will show all errors at once instead of failing on first one, installer will be able to try to fix all instead of fixing one at a time and trying again.
writeConf(): added if LACONICA is !defined exit

Tests: drop database and remove config.php, ran installer. Passed.