Getting started with LLT / Deploying WAR

[oakenshield]

Hello,
I would like to experiment with LLT. Iam quite familiar with Java-based Web-Services but entire new to (j)ruby. I got quite far, added missing gems, jars etc. until I got stuck: When I attempt to run service I get the exception in the tomcat log:

LoadError: no such file to load -- nokogiri/nokogiri
require at org/jruby/RubyKernel.java:1071
(root) at /var/lib/tomcat7/webapps/ROOT/WEB-INF/gems/gems/nokogiri-1.6.5/lib/nokogiri.rb:29

If I comment out the require nokogiri/nokogiri it will find nokogiri/version but then complain about an undefined constant: Nokogiri::XERCES_VERSION

Some Variables from the log:
--- System
jruby 1.7.17 (2.0.0p195) 2014-12-09 fafd1a7 on Java HotSpot(TM) 64-Bit Server VM 1.8.0_25-b17 +jit [linux-amd64]
Time: 2014-12-22 14:47:31 +0100
Server: Apache Tomcat/7.0.52 (Ubuntu)
jruby.home: file:/var/lib/tomcat7/webapps/ROOT/WEB-INF/lib/jruby-stdlib-1.7.17.jar!/META-INF/jruby.home

--- Context Init Parameters:
jruby.compat.version = 2.0
public.root = /
rack.env = production

I have build the project based on a clone of https://github.com/latin-language-toolkit/llt

Does this error sound familiar? I guess Iam just missing something because Iam new to ruby. Is there any documentation about setting up the project I missed?

Best wishes,

Rüdiger