Support more than one devices for flash_local.py
Merge pull request #294 from askeing/support_more_devices_for_flash_local

Support more than one devices for flash_local.py
Changed the flash seq from "gaia->gecko" to "gecko->gaia".
Added /system/b2g/defaults/ and /system/b2g/webapps/ to white list of clean_extra_gecko_files().
fixed #295
Merge pull request #296 from askeing/fix_295

Changed the flash seq from "gaia->gecko" to "gecko->gaia". Added "webapps" and "defaults" into white list of clean gecko method.