Makefile mishandles precise and i386

[Curtis Hovey]

The install-dependencies adds ppa for golang and juju stable. We officially recommend the cloud-tools archive for precise and it has the packages we require.

Since cloud-tools gets new packages without announcement, the juju stable PPA can have older packages that users are not going to get. The golang deps could continue to come from the golang PPA, but we actually develop and test with the experimental PPA and copy the proven packages to the other archives.

Also, the x86 rules are wrong to match compilers. the run-unit-tests scripts do this
    sed -i 's/x86/86/' Makefile
before running macke

These changes are need because run-unit-tests are getting a refactoring to simplify their responsabilties.