geth: add a new package

The package was tested on raspberry pi 3. Geth needs about two hours to
fully sync the first try and uses an additional 250Mb of storage.

Signed-off-by: Mislav Novakovic <mislav.novakovic@sartura.hr>

net/geth/files/geth.init

@@ -0,0 +1,15 @@
+#!/bin/sh /etc/rc.common
+
+START=90
+STOP=10
+
+USE_PROCD=1
+PROG=/usr/bin/geth
+
+start_service() {
+    procd_open_instance
+    procd_set_param command ${PROG}
+    procd_append_param command --syncmode "light" --cache 1024
+    procd_set_param respawn
+    procd_close_instance
+}