ClassNotFoundException when using User Libraries in Eclipse build path
Solution 1:
In project's properties, go to Deployment Assembly. Add there the buildpath entries as well which you've manually added as user libraries. It'll end up in /WEB-INF/lib of the deployed WAR.
Solution 2:
You'll need to copy the jar files to the WEB-INF/lib folder: that is where they are supposed to be.
Eclipse should offer you the option of generating a WAR file that includes all the dependencies: I haven't used Web Tools for a good while but one way or another all dependencies have to be in WEB-INF/lib or the class loader won't be able to find them.