Song Integration Part 1

- modal view
- integration of display functions
- fixed model problems
Home page link changes
SCHEMA CHANGE - ADDED PURCHASE TYPE
Merge branch 'master' of https://github.com/gswetha/cs2102

Conflicts:
	application/views/home_page.php
Merge branch 'master' of https://github.com/gswetha/cs2102

Conflicts:
	application/views/home_page.php