minor code review fixes
fix occasional comodification error in tests
standardise the names of webapp sensors
expose Application from the AppBuilder for use in doBuild to attach policies, sensors, etc
includes some "key performance" high-level sensors on the app;
removes an (unuseful) Alt.java example, and adds an App.java
remove the getApplication method i introduced as getApp is already there (i just missed it)
further fix for BasicTaskExecutionTest synch
comment for code review
Merge pull request #509 from ahgittin/fix/new-entity-model-nicer-groovy

minor code review fixes, and adding KPI