Convert ACLGuard to use a single-file protobuf instead of two files.

This commit adds back in the protobuf-serialization format used for ACLGuard in
the C++ Tao. It converts ACLGuard to use this format for its signed data, and it
fixes the tests to conform to this style, as well.
Add ACLGuard support to Domain
Add a test for an empty ACL, and add simple Domain tests.

This change adds tests for the Domain Save/Load methods and fixes a bug that was
getting the wrong path for the domain keys; it was inconsistent between two
locations in the code. This made the ACLGuard fail its verification check.
Refactor the tao net code out of demo, and fix the install to set up an AIK properly
Add hybrid sealed data and fix the install script to support TPM.

This commit adds support for TPM-based tests using install.sh -tpm.
It adds a new hybrid sealing scheme in TPMTao to overcome a limit in the number
of bytes that can be sealed in the hardware TPM; to do this, it creates a new
key (using Crypter in keys.go), encrypts the data using this key, and seals the
serialized key structure as the sealed data. Unseal reverses the operation.

This version also changes the host to not try to extend the name of the Tao in
the Stacked LinuxHost when the Tao is TPMTao. This is OK because TPMTao already
extends its name with the PCR values, which characterize the Linux OS in
question (or at least, they do if we boot from initrd).
Move the Go source up to the top directory to match standard Go style.

This commit also rewrites the import paths under the assumption that the code
will live under ${GOPATH}/github.com/jlmucb, as usual for github code.
Add Tao network Dial/Listen functions.

This commits adds Tao Dial/Listen functions that set up a connection with
authorization that uses Tao attestations. These channels set up a TLS channel
then exchange Tao attestations on the channel and check that the remote program
is authorized to execute and that the certificate used for the TLS exchange is
properly delegated by the authorized program using the given Tao Attestations.
Fix minor inconsistency in the install.sh comments