Changed the Flight Constructor

Modified the flight constructor to receive flight type as a string and
then create a new instance of FlightType using the flight type string.
Modified DB_Interface

Changed DB_Interface to be more general so that it can be used for both
the Stub DB and the HSQLDB.
Modified Flight Test to reflect changes to Flight

Change FlightTest to send flight type as a string to the flight
constructor.
Re-Created the Database

After strange synchronization problem, the database was not present in
the repository.  Re-added it.
Modifed the classpath.

The classpath had links to jar files that are not present in the lib
directory.