Fix #112 : Fix Log4J 2.x compat issue with some Servlet 3.0+ containers.

- It's a temporary workaround till the upstream issue gets fixed :
https://issues.apache.org/jira/browse/LOG4J2-432
Fix CUP version conflict(i.e. xalan.jar) in some environment.

As different version of JavaCup libraries are bundled by several other
libraries (i.e. xalan), there has been such problems like
NoSuchMethodError thrown in certain environment depending on library
orders in the runtime classpath.

This change eliminate such a problem by adding certain methods to
CupParser class which are not present in an earlier version of JavaCup
library.
Workaround for a Jetty's problem of not invoking @PostConstruct.

Jetty seems not to call @PostConstruct defined in an abstract parent
class.