build: Default to python2

On some systems, /usr/bin/env python is default to python3, specifiy
python2 to fix that

Change-Id: Ieecb98d69b0e9e958042622b97826d1ba6ef672c
build: Improve roomservice

roomservice has improved in the sense that once a duplicate path is
found, a <remove-project> tag will be added into roomservice.xml

Change-Id: If3e1dc672d25996a0cd19628ece24c010e213adf