Remove the PluginSystem

But keep the Interface so it's still userfull to create a new
SocialNetwork  when needed, but it will be part of the code,
and not a plugin.

Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

subsurface-core/CMakeLists.txt

@@ -79,6 +79,7 @@ set(SUBSURFACE_CORE_LIB_SRCS
 	color.cpp
 	pluginmanager.cpp
 	imagedownloader.cpp
+	isocialnetworkintegration.cpp
 	${SERIAL_FTDI}
 	${PLATFORM_SRC}
 	${BT_CORE_SRC_FILES}