Packaging changes for updated Go package.

- package name changed to 'nginx/unit';
- source files installed in /usr/share/gocode;
- rpm and deb go packages made noarch.

pkg/deb/debian/unit.example-go-app

@@ -3,7 +3,7 @@ package main
 import (
     "fmt"
     "net/http"
-    "unit"
+    "nginx/unit"
 )
 
 func handler(w http.ResponseWriter, r *http.Request) {