The PrivateSignatory class becomes abstract and base of the classes
PlainPrivateSignatory and EncryptedPrivateSignatory. 

PlainPrivateSignatory acts as the old PrivateSignatory with the
unencrypted private key.
Persistence secret key management.
GUI menu options for the passphrase management.
Passphrase management arrangements.
Upated references to the upgraded Berkeley DB jar file on the ant xml
files.
Merge branch 'passphrase'