Add memory and limit support

* This adds `${Problem.MemoryLimitMB}` , `${Problem.TimeLimitMillis}` and `${Problem.TimeLimitSeconds}`.
* Add limits section to problem statement.
* build system now uses the latest jars, turns out we need to use them instead of ContestApplet.conf: http://apps.topcoder.com/forums/?module=Thread&threadID=806641&start=30