Distribute database initialization routines

[piotras]

midgard-php5 extension should include simple database initialization scripts. One could be based on MidgardBootstrap introduced in phpcr-midgard2: https://github.com/midgardproject/phpcr-midgard2/blob/master/MidgardBootstrap.php.
Practical use case is to keep any API changes in one place and initialize repository with uniform manner.