Added ValidateManager and its associated files.
files added: ValidateManager.h, ValidateManager.c, constants.h
comment: ValidateManager has extensive validations, so I'll start with
incorporating it now. One of the best feature of this ValidateManager is that it  has
extensive validations for Url, for example, it validates:
* valid: http://www.deanza.edu
* valid: http://deanza.edu
* valid: www.deanza.edu
* invalid: deanza.edu.
* invalid: .deanza.edu
* invalid: deanzaedu

TODO: incorporate ValidateManager