reorganizing the build plan classes a little bit
introduced the IBuildPlan interface, implemented LiteralPlan a little bit
deeper tests of ConcreteBuild w/ children
renaming the temporary BuildPlanClasses
renamed IBuildStep to IDependencySource
ripped out the old BuildFrame/BuildStack functionality.  Closes GH-107
IBuildPlan now uses IBuildSession instead of IContext
worked over the signature of IDependencySource, can now resolve from lifecycle
reorg-ing classes in the Building namespace after implementation work
got the ArrayDependencySource working
added the array and list dependency sources
very mild cleanup on build plan classes and moved ILifecycleContext out