auth: add set_uid() to KeyRing, print out auid in print function

src/auth/KeyRing.cc

@@ -68,6 +68,7 @@ void KeyRing::print(ostream& out)
        p != keys.end();
        ++p) {
     out << p->first << std::endl;
+    out << "\tauid: " << p->second.auid << std::endl;
     out << "\tkey: " << p->second.key << std::endl;
 
     for (map<string, bufferlist>::iterator q = p->second.caps.begin();

src/auth/KeyRing.h

@@ -55,6 +55,9 @@ public:
   void set_caps(EntityName& name, map<string, bufferlist>& caps) {
     keys[name].caps = caps;
   }
+  void set_uid(EntityName& ename, __u64 auid) {
+    keys[ename].auid = auid;
+  }
   void import(KeyRing& other);
 
   // encoders