Fix for #17 - Provide additional information

When first loading the webpage, database may not have any data in it,
this provides additional details on how to load the data.

https://github.com/sc2balance/SC2Balance/issues/17

I rethrew the error with additional data because this will occur very
rarely and be seen only by developers. No need for a pretty screen.
Merge pull request #18 from nathankoop/master

Fix for #17 - Provide additional information