Create primary (first-stage) loader for runtime environment checks

Begins #1531
Add newline to end of bootstrap.php
Modify front controller to call primary loader
Modify Nut to call primary loader
Add load chain test to ensure that load.php invokes bootstrap.php
Wrap the bootstrapper in a closure which returns $app back out
Merge #1531

Conflicts:
	app/bootstrap.php
Merge #1530

Conflicts:
	app/bootstrap.php