Added php composer for autoloading packages and files

Composer was selected to make it easier to include files in our application site-wide without having to make "require" statements anywhere we want those files. Now as we add more file like controllers or models, we don't have to manually load those, composer autoloader handles that for us
Refactored bootstrap to make it easily testable and to take advantage of composers autoloader feature
Add test file for bootstrap and tested "extract_url_segment" function in Bootstrap class