fix #1105 add development mode icon

src/main/java/org/codelibs/fess/es/client/FessEsClient.java

src/main/java/org/codelibs/fess/helper/SystemHelper.java

...ain/java/org/codelibs/fess/mylasta/action/FessLabels.java

.../java/org/codelibs/fess/mylasta/direction/FessConfig.java

src/main/resources/fess_config.properties

src/main/resources/fess_label.properties

src/main/resources/fess_label_en.properties

src/main/resources/fess_label_ja.properties

src/main/webapp/WEB-INF/view/common/admin/header.jsp

src/main/webapp/js/admin/admin.js