Removed hard-coding of color values

Use color values defined in XML files to set foreground/background
colors of TextView entries.
Used inflater to in Adapter's getView() method

Instead of calling the parent class' getView the custom adapter now
calls the inflater to create a list item view (if necessary).

The item separator in the list view was also reduced to zero - disabling
the list item seemed to make the separator disappear so might as well
disable separators to start with.