Make merge.py use build.default.config and also clean.
Make merge.py use build.default.config and also clean.

Related issue: #292

IoT.js-DCO-1.0-Signed-off-by: Ilyong Cho ily.cho@samsung.com

chunseoklee/iotjs,lemmaa/iotjs,qdk0901/iotjs,wateret/iotjs,wateret/iotjs,wateret/iotjs,lemmaa/iotjs,chunseoklee/iotjs,lemmaa/iotjs,qdk0901/iotjs,qdk0901/iotjs,chunseoklee/iotjs