fix syntax errors in datamapper
fix a bug in User
injecting a database abstract layer (instead of creting it in constructor)
making a unit test class with mockup instead of unfinished script
adding test for find
bugfix in UserMapper
test restore with find
bugfix in UserMapper::findAll
don't repeat yourself
using exception instead of null return (preventing potential NPE)
remove buggy test script
PHP 5.3 compatibility
grammatical correction
Merge pull request #25 from nandeeshmp/patch-1

grammatical correction
full visitor pattern withh double dispatch
strong typing based on interface, not object
documentation (commiting now from Guadeloupe)
some comments and refactoring for D.R.Y
PSR-0 compliance
unit testing with PHPUnit