[TORQUE-987] Torquebox under Windows is case sensitive to the PATH environmental variable

This should fix https://issues.jboss.org/browse/TORQUE-987.

The problem is that we receive the environment variables and store in a HashMap and afterwards we try to get a value from it. In case of Windows we end up (most probably) with a key `Path`, executing `.get("PATH")` on that HashMap will return `null`. Instead we should use `System.getenv("PATH")` call which is case insensitive.

This needs some testing on Windows.