mm: add build.gradle and add .gitignore

add gradle build system and add .gitignore .gradle/ folder

Signed-off-by: KyungKoo Kang <kyungkoo.kang@yahoo.com>
Merge branch 'master' of https://github.com/GDG-Korea/gdg_codelab_1403
Added: gitignore For Sublime Text

Sublime Text 프로젝트 기능 쓰시는 분들을 위해 미리 추가합니다.
Signed-off-by: seonggwang.gwon <g.passcode@gmail.com>
Merge pull request #29 from kyungkoo/master

add build.gradle and add .gitignore
Merge pull request #38 from seonggwang/gitignore_sublimetext

Added: gitignore For Sublime Text
Merge remote-tracking branch 'gdg/master'