Added log for authorization failure of proposal operations

libraries/chain/proposal_object.cpp

@@ -43,6 +43,7 @@ bool proposal_object::is_authorized_to_execute(database& db) const
    } 
    catch ( const fc::exception& e )
    {
+      elog( "caught exception ${e} while checking authorization of proposal operations",("e", e.to_detail_string()) );
       return false;
    }
    return true;