core: moved __version__ to __init__.py, so we can check version by doing "import sat;print(sat.__version__)"

src/__init__.py

@@ -0,0 +1,3 @@
+from core.constants import Const as C
+
+__version__ = C.APP_VERSION

src/core/sat_main.py

@@ -48,9 +48,6 @@ except ImportError:
     from ordereddict import OrderedDict
 
 
-__version__ = C.APP_VERSION
-
-
 class SAT(service.Service):
 
     @property