Initial log framework

Also:

- Renamed voltha.py to main.py (due to module collision)
- Added logging related dependencies
- Twisted loop
diff --git a/build.gradle b/build.gradle
index 83c07b9..9fb6546 100644
--- a/build.gradle
+++ b/build.gradle
@@ -50,8 +50,8 @@
 // ~~~~~~~~~~~~~~~~~~~ Global tasks ~~~~~~~~~~~~~~~~~~~~~~~
 
 // To be used to fetch upstream binaries, clone repos, etc.
-task fetch {
-    // ...
+task fetch(type: Exec) {
+    commandLine "make", "fetch"
 }
 
 // To be used to generate all needed binaries that need to be present on the target