https://github.com/watanabear/android_tips/blob/master/OSS%E4%B8%80%E8%A6%A7.md
http://qiita.com/kgmyshin/items/5d92915b3d0b8c69cfd4
# Built application files
/*/build/
# Crashlytics configuations
com_crashlytics_export_strings.xml
# Local configuration file (sdk path, etc)
local.properties
# Gradle generated files
.gradle/
# Signing files
.signing/
# User-specific configurations
.idea/libraries/
.idea/workspace.xml
.idea/tasks.xml
.idea/.name
.idea/compiler.xml
.idea/copyright/profiles_settings.xml
.idea/encodings.xml
.idea/misc.xml
.idea/modules.xml
.idea/scopes/scope_settings.xml
.idea/vcs.xml
*.iml
# OS-specific files
.DS_Store
.DS_Store?
._*
.Spotlight-V100
.Trashes
ehthumbs.db
Thumbs.db