Update release gpg sign key
Bump version to 0.16.0 ... do not use version 0.15.0

The use of version-info conflicted with the naming
convention used to represent libqb version numbers. Because
of this the shared library file used for release 0.15.0
did not properly match the release version.  From now on
the version number will be manually set to guarantee consistency
between .so file and release version.