Allows for multiple spec target definitions in the thrust.yml.

Breaks the previous trust.yml configuration format - requires an upgraded thrust.yml config file as described in the README.md.
Adds 'nof' and 'focused_specs' tasks for cedar

Updates all puts statements to go to STDERR so that it's output will not conflict with system output.
Forces the build root to be 'build' under the project.
Adds a rake task to show the current version of the app.
Makes spec tasks depend on the clean task.