Initial work on a RetroShare cross-platform service

This doesn't need any interacion of the user at startup, unlike
retroshare-nogui which requires the user to login on the shell this doesn't
even need a TTY.
At startup this just parse command line, read the PGP keyring, look for
available locations, and start listening for JSON API requests.
Another difference with retroshare-nogui is that this is capable to
generate/import PGP identities, generate locations, and in general anything
possible through the RetroShare API.
retroshare-service is suitable also to run it as a system service, even
in very constrained systems such as Android ot a Docker container.
retroshare-service drop support for libresapi so only the new JSON API
is exposed, it will completely obsolete retroshare-android-service once
retroshare-qml-app is ported to the new JSON API.

libretroshare/src/use_libretroshare.pri

@@ -57,9 +57,7 @@ rs_jsonapi {
     QMAKE_LIBDIR *= $$clean_path($${RESTBED_BUILD_PATH}/library/)
     # Using sLibs would fail as librestbed.a is generated at compile-time
     LIBS *= -L$$clean_path($${RESTBED_BUILD_PATH}/library/) -lrestbed
-    win32-g++ {
-	LIBS += -lwsock32
-    }
+    win32-g++:LIBS += -lwsock32
 }
 
 linux-* {