Simplify the recipe commands interface: * The implementation of a command is now located using a pseudo-protocol for namespace URIs. * Commands are simply module-level functions instead of components. * Remove dependency of the recipe/slave code on the Trac component architecture.

[unittest]
test-suite = bitten.tests
xml-results = build/test-results.xml
coverage-results = build/test-coverage.txt
coverage-dir = build/coverage