Don't checkout SIGCOMM branch. (#62)

* Created new subdirectory for Fall developer day.

* Created vm directory for P4D2_2017_Fall. Fixed emacs permission problem.

* Remove checkout of SIGCOMM branch.

P4D2_2017_Fall/vm/user-bootstrap.sh

@@ -38,7 +38,6 @@ cd ..
 pip install crcmod
 git clone https://github.com/p4lang/tutorials
 cd tutorials
-git checkout sigcomm_17
 cd ..
 sudo mv tutorials /home/p4
 sudo chown -R p4:p4 /home/p4/tutorials