Put more controls in the GUI. Is able to search for arff files via file
chooser. Added an Attribute class to hold attribute data. Created a
relation class to store complete relation data from the file. Created a
class to actually read from the file and put data where it belongs.

Some of this is questionable. Much of this may change depending on what
we actually need to DO to this data. This is a good start to be able to
access the data.