Added ability to dump/load all policies at once

Previously there was no way to load policies from disk
into the policy engine or to dump policies to disk.

This change adds the ability to do so.  Each Theory class
now has the following functions.
o  policy(): returns any policy statements the theory represents
o  contents(): returns any policy or data the theory represents
o  __str__(): prints the theory in a form that can be parsed.
Different subclasses of Theory differ in whether they print
policy() or contents().

The Runtime class includes functions for loading/dumping
a particular file into a particular theory and for loading/dumping
all policies into a directory where each policy corresponds
to a file with the same name.

Change-Id: Ie80be4047b3798194aa8fab5fbcf29f858534609
Merge "Added ability to dump/load all policies at once"