Hi there!
Bad class version usually means that your class files (from the war) have been compiled to target newer version of java from the version your app server supports.
As far as I remember at this point, Websphere 8.5 works with java6? And uphea war may be built with java7 :) Hence the issue.
To resolve this, you would need to rebuild uphea to java 6, although I am not sure if this is possible (since we are using some java7 syntax)...
Anyway, current version of uphea example is bit old (we haven't upgraded yet;), so you might try instead simple quickstarters (see github repo). These examples are very simple comparing to uphea, but at least you can start to play with it on websphere ;)
I hope this helps!