URL rewriting functionality for Parrot

Introducing URL rewriting to Parrot. It works by redirecting requests from Parrot/page to Parrot/app/page.php internally.

Changes include:
	- .htacess now included in versioning, contains necessary rewrite rules;
	- index.php now acts as controller. All non-existing file requests are redirected to explore.php;
	- js/Contstants.js changed so that data urls are no longer looking for data folder one level up.