Optimize Action System

When profiling JSF WebApp a lot of time is spent in the action system.
This makes sens since actions are used a lot during page construction.
But the profiler shows that we spend most of the time creating el expressions rather than evaluating them.

The ratio is really significant 85% of the time is spent in el expression creation.parsing.
The apache el doc does not say is el expression is threadsafe or not : by default, I assume they are not.
See an attached "patch" for that.