Support GCC 4.7

Removed constructors inheritance.
Removed emplace use.

Change-Id: I45224e3232d39ff22f758c7e387be2c9aff5eae0
Reviewed-on: https://weave-review.googlesource.com/1606
Reviewed-by: Vitaly Buka <vitalybuka@google.com>
diff --git a/src/commands/command_dictionary.cc b/src/commands/command_dictionary.cc
index 8fb7f43..516961f 100644
--- a/src/commands/command_dictionary.cc
+++ b/src/commands/command_dictionary.cc
@@ -62,7 +62,8 @@
         return false;
       }
 
-      new_defs.emplace(full_command_name, std::move(command_def));
+      new_defs.insert(
+          std::make_pair(full_command_name, std::move(command_def)));
       command_iter.Advance();
     }
     package_iter.Advance();
@@ -81,7 +82,7 @@
 
   // Insert new definitions into the global map.
   for (auto& pair : new_defs)
-    definitions_.emplace(pair.first, std::move(pair.second));
+    definitions_.insert(std::make_pair(pair.first, std::move(pair.second)));
   return true;
 }