Cleanup src_plugin_sdk directory

- No need to copy local files
- No need to keep local copy of 'etherum-plugin-sdk' files
- Select needed files directly from the Makefile

tools/build_sdk.sh

@@ -1,10 +0,0 @@
-#!/bin/bash
-
-# Clean the sdk
-find ./ethereum-plugin-sdk/ -mindepth 1 -maxdepth 1 ! -name .git -exec rm -r {} \;
-
-# Copy exclusive files
-cp -r src_plugin_sdk/* ./ethereum-plugin-sdk/
-
-# Copy common sources
-cp -r src_common/* ./ethereum-plugin-sdk/src/