Update android-support-v4.jar to match actionbarsherlock.
Copy rather than move files going to system because Android's mv won't work across mount points.
Copy sftp_server to /usr/libexec so that people don't have to use additional parameters to get sftp to run.
Allow the clean-up of ssh/scp/etc by making /system rw, and add the removal of sftp_server as well.