Update lab07.md
Update lab07.md

Updating Lab 7 with updated submit.cs link
ucsb-cmptgcs-1a-f17/ucsb-cmptgcs-1a-f17.github.io,ucsb-cmptgcs-1a-f17/ucsb-cmptgcs-1a-f17.github.io,ucsb-cmptgcs-1a-f17/ucsb-cmptgcs-1a-f17.github.io,ucsb-cmptgcs-1a-f17/ucsb-cmptgcs-1a-f17.github.io,ucsb-cmptgcs-1a-f17/ucsb-cmptgcs-1a-f17.github.io,ucsb-cmptgcs-1a-f17/ucsb-cmptgcs-1a-f17.github.io