Change the internals of the Identity class. Instead of a separate member var for each setting, use a QHash<QString,QVariant> to store them.

This system opens up the possibility to store random settings for Identities (property()/setProperty()), which is needed for other applications than KMail to use this library.

Also remove the HAVE_GPGME compile time check, so this library does no longer depend on kdepim/kleo/any GPL application and thus making this library LGPL.