Switch to composer (http://getcomposer.org) in external libraries usage.

As agreed in this topic (http://qcu.be/content/new-roadmap) the composer should be adopted for qcubed distribution and it]s own dependencies as well.
The first step in this direction is taken: the two external libraries - htmlpurifier and simpletest are replaced with composer dependencies.
See http://getcomposer.org/doc/00-intro.md#installation-nix for information on how to install and http://getcomposer.org/doc/00-intro.md#using-composer to use composer.
Generally, after (global) installation you should do just "composer install" in order to make your qcubed installation fully equipped with all it's dependencies.
The UNIQUE indexes creation was done incorrectly for the type-table creation.
Move composer files to includes directory

The composer files and the vendor directory created by "composer install" command has been moved to includes directory to allow secure qcubed installs.
Merge pull request #61 from olegabr/feature-Composer

Feature composer