The CM can now receive either an ABAC or a non-ABAC speaksfor
credential in the list of credentials. Thanks to Gary for getting
libabac built on boss so that I could use it! The AM probably needs a
little bit more work since it has a few V3 places where it does not
invoke CMV2 directly, but that should be easy to fix; all of the AMV2
functions will work tough.

Caveat; I don't bother to look at the speaksfor option; if we get a
speaksfor credential, I figure it was cause the user wants to use it!

I added a hacky script called genspeaksfor to create a proper speaks
for credential that allows me to speak for another user. For example:

	genspeaksfor -a urn:publicid:IDN+emulab.net+user+leebee \
	         urn:publicid:IDN+emulab.net+user+stoller

which generates an ABAC speaks for credential that allows me to spead
for leebee. To use the PG test scripts with this credential:

	createsliver.py* -S speaksfor.cred -s slice.cred

Where slice.cred is a plain slice credential issued to leebee and then
given to me via an out of band mechanism (:-).