Add indeterminate variables for implementation of inspectors and incremental updates

[monsanto]

When I was originally working on this compiler, we had come up with an mechanism of "unresolved" or "indeterminate" variables in policies to allow higher level inspectors to enjoy incremental compilation (instead of regenerating the entire policy over and over again). We should collectively try to remember the consensus and come up with a plan for implementation.

Feel free to assign this task to me ATM.