Add System class

This class is used to call stuff on the terminal using the system() function in a much easier and elegant way.
Add System::realpath()

System::realpath() returns the path to a specific executable.
Better output in the system/execute.php example

Now uses print_r() instead of var_dump() for an array.
Test not executable but existing files in SystemTest.php
Add the System class to the Toolkit class aliases
Merge pull request #8 from vis7mac/system

Add System class