Create wrapper package for fcitx with plugins.

This creates a wrapper package for fcitx so that plugins can be enabled
by the user.  This is based on the wrapper package for
pidgin-with-plugins.

By using this wrapper instead of the fcitx package itself, it will be
possible for the user to enable/disable plugins.
Merge pull request #4839 from cdepillabout/fcitx-with-plugins-2

Create wrapper package for fcitx with plugins.