Applicant Fuhong Liu's pull request

### This pull request include the following changes.


**Part I**

  1. AbstractModel.php was built to include the abstract class that used by Contact.
  2. The database calls are made through MySQLi.

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 **Part II**

  1. The [Slim framework](http://www.slimframework.com/) was chose for it is a light-weighted framework yet still provides capability of url routing and template rendering with custom views.
  2. The app is running on an Amazon micro instance.
  3. A web page was created to list all the contacts in database ([http://ec2-54-227-171-124.compute-1.amazonaws.com/contact/list](http://ec2-54-227-171-124.compute-1.amazonaws.com/contact/list)).
  4. The web page for viewing contacts are located at http://ec2-54-227-171-124.compute-1.amazonaws.com/contact/view/[some_id]

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**Part III. GitHub**
  1. I'm creating the pull request to original repository. Thanks!