Update notes for submitted changes

* mcf: Simplify updaterepo function
* mcf: Remove update parameter from downloadrepo function
* mcf: Don't unnecessary call git remote update
* mcf: Read weboslayers.py just once and verify MACHINE values
* build.sh: Show buildhistory branch and allow to change prefix (v4.0.1)
* mcf: Add sanity check for git mirrors, premirrors and sstatemirrors
* mcf: Fix setting tracking branch
* mcf: Change remote url when weboslayers.py sets different one
* mcf: Use 4th param in weboslayers.py as DIRNAME for checkout
* mcf: Change default command to update as well as configure
* mcf: Use logger instead of calling print directly