SELinux support (at least on some ROMs) + root fixes

* Added menu option to symlink hosts file to /data/hosts
* Added setting SELinux context on symlink target
* Fixed ANRs/crashes while doing root commands (at least on some ROMs; may require testing on others)

This should solve issue #521 and probably issue #492

With this patch /data/hosts target file should work on Android 4.4 (tested on CM11 nightly). Also stability while doing root commands is improved.