Fix bug: Wrong COUNT query for OrientDB

Query was taking too long to execute.

lib/orient_db/methods/edge_methods.rb

@@ -5,7 +5,7 @@ module OrientDb
       ##
       # Count the number of edges existent
       def get_in_edges_count(edge_class, id)
-        result = connection.query "SELECT COUNT(@rid) FROM #{edge_class} WHERE in = #{id}"
+        result = connection.query "SELECT IN('#{edge_class}').size() AS COUNT FROM Object WHERE @rid = #{id} LIMIT 1"
         result.first["COUNT"].to_i
       end