NOJIRA - Update README

Couple of fixes:

* Make the Java 7 requirement more explicit. 2 students have tripped over this
* Use the right name for ojdbc6.jar
* Leave a note that mentions that they don't really have to do the steps after the development steps. The students have install memcached / torquebox when they don't really have to.
Merge pull request #2282 from christianv/nojira-fix-readme

NOJIRA - Update README