Fix rare crash when su is missing
Add isSELinuxEnforcing() method, caches result
Change Shell.SU.version(boolean internal) method to cache its result
Add Shell.SU.clearCachedResults() method
Update .gitignore
Update copyright years
Restrict shellMountMaster() to only return --mount-master on 4.2+
Add gradle build files

Signed-off-by: Jorrit Jongma <git@jongma.org>
Update gitignore for gradle
Add gradle wrapper (http://www.gradle.org/docs/current/userguide/gradle_wrapper.html)

Signed-off-by: Jorrit Jongma <git@jongma.org>
Update gradle

Signed-off-by: Jorrit Jongma <git@jongma.org>
Update target SDK to 19, min sdk remains at 4
Whitespace adjustments to example AndroidManifest
Per-command line listener for interactive shell implemented