#2 ClassLoader isolation for Task extensions

[Justin Ferris]

Task extensions are loaded with the same ClassLoader as
that used to load Freefluo classes. This means that
custom task extensions are unable to be used if they rely
on libraries that are incompatible with libraries that
Freefluo relies upon.

We need to use a simple Tomcat-like ClassLoader
isolation mechanism so that Task extensions with complex
incompatible dependencies can be deployed to freefluo.

[Justin Ferris]

Logged In: YES
user_id=696176

A custom ClassLoader that extends URLClassLoader has been
written. Freefluo now supports different engine configurations.
An engine configuration provides a workflow parser and data
handler. All classes loaded by the workflow parser are loaded
with the classloader that's associated with the configuration.
This means that configurations are isolated from each other
and the classes that make up freefluo. However, task
extensions within a particular configuration share the same
class loader at present.