Merge pull request #76 from askeing/master

Modified the comment of auto_flash_from_PVT.sh
DEBUG=1 will by pass auto checkout master and auto pull.
Merge pull request #78 from askeing/by-pass-auto-pull-of-auto-flash-pvt

DEBUG=1 will by pass auto checkout master and auto pull.
Merge remote-tracking branch 'mozilla/master' into fix_fetch_gecko_name_function_for_mac