Store ca cert, user cert and user rsa key into Context KeyChain
MeanderingCode needs certs stored that way, along with rsa key from user cert.
Right now, rsa key is not separated from user cert, and all three are stored in SharedPrefs.
Reference: http://developer.android.com/reference/android/security/KeyChain.html
(from redmine: created on 2013-05-16, closed on 2013-06-02)