Comply with Harbour app name requirement

The app name must be prefixed with "harbour-". Since the current
version of the app SDK makes some silly assumptions on matching
TARGET & .pro file names, using the same name for TARGET, .pro,
.desktop etc. works best in the way that all install targets etc.
provided by mkspecs/features/sailfishapp.prf work out of the box.
import Communi => harbour.communi
Get rid of the silly "pages" subfolder

We only had one page, but several non-page components there. Now
after the harbour-prefix change is a perfect time for retructuring,
since devs need to do a clean build from scratch anyway.
Store settings within $XDG_CONFIG_HOME/$NAME
Qt.labs.settings => harbour.communi.settings