BERLIN (Reuters) - Angela Merkel and Francois Hollande presented a united front towards Greece on Thursday, telling Athens it should not expect leeway on its bailout agreement unless it sticks to tough reform targets. The German and French leaders met in Berlin to fine-tune their message to Prime Minister Antonis Samaras, who begins a charm offensive in Berlin and Paris this week in the hope of persuading Europe's big powers that Greece deserves patience. Merkel stuck to her policy of deferring to a report due in September on Athens' progress by the "troika" of international lenders before discussing flexibility on the bailout terms, but said it was vital "that we all stay true to our...