add encryptAndSign method to force signing with encryption
add encryptAndSign method to force signing with encryption

eighthave/gnupg-for-java,guardianproject/gnupg-for-java,HellUnit/gnupg-for-java,eighthave/gnupg-for-java,HellUnit/gnupg-for-java,guardianproject/gnupg-for-java,HellUnit/gnupg-for-java,guardianproject/gnupg-for-java,eighthave/gnupg-for-java,HellUnit/gnupg-for-java