[DB] H2 embedded database

-H2 is now the default (embedded) db
-Removed HSQL files
-Installer folder now contains only the installation script, which is
obsolete. To be updated with H2 support
-Updated pom.xml. The build process copies a clean H2 db if it doesn't
already exists. Local DB path must be set here
-Fixed Birt report template with parametric DB credentials