Switch to genaik from tpm_tao.

This commit removes the last dependency of the Go CloudProxy Tao on the C++
CloudProxy Tao: it uses the latest version of github.com/google/go-tpm/tpm to
generate an AIK instead of relying on TrouSerS to do this.
Explain integration-test install process.

This commit adds a file that explains how to install the simple integration
tests set up by install.sh, including how to get the TPM set up and some tips
and tricks for working with the Datalog version of the tests.