Fixed makefile and added "offsets" output format 

The makefile had a hardcoded path to servlet-api.jar in /opt/tomcat which is not where my tomcat lives. I committed the jar to the repo instead so it should work for anyone. The makefile also uses pushd and popd which made it fail on my system until I added "SHELL = /bin/bash"

I made it so you can set "outputFormat=offsets" in a post and it will output the results of the classifyToCharacterOffsets() method. This makes it tell you the positions in the document where it finds things, instead of adding markup to the text of the document.

I also made it wrap exceptions when rethrowing so the stacktraces contain as much info as possible (almost always a good idea).