Created WebUtils class for implementing the connection to a web service, and changed the download/waiting from a dialog into a panel.

Removed the HTTP-download specific code from YahooFinanceAPI and placed it in a new WebUtils class which should now contain the implementation for retrieving data from a web service.

When the "please wait while downloading" message was in a modal dialog, the user was not able to close the main window (ie. shutdown the program). By incorporating this into the main window, the user can still shutdown the program if they want.