Wonho

-   The module - 'skills' is updated. Now the SkillMapper class
    smoothly interects with the Skill family classes. SkillPHD.java
    file is added there. Test module is also updated to test the
    interection between SkillMapper and Skill family classes. To test
    this use 'make skills' command at the root directory.

-   Log file - 'updates/updates_by_wono.log' is updated.