Introduce module financer-common that hosts common code for server and (web) client

Also various fixes all over the place

financer-web-client/src/main/resources/templates/recurringTransaction/recurringTransactionList.html

@@ -30,8 +30,8 @@
         <td>
             <a th:href="@{/accountDetails(key=${rt.toAccount.key})}" th:text="${rt.toAccount.key}"/>
         </td>
-        <td th:text="${rt.firstOccurrence}"/>
-        <td th:text="${rt.lastOccurrence}"/>
+        <td th:text="${#temporals.format(rt.firstOccurrence)}"/>
+        <td th:text="${#temporals.format(rt.lastOccurrence)}"/>
         <td th:text="${#numbers.formatDecimal(rt.amount/100D, 1, 'DEFAULT', 2, 'DEFAULT')}"/>
         <td th:text="${rt.description}"/>
         <td th:text="#{'financer.interval-type.' + ${rt.intervalType}}"/>