Merge tag '1.4.9' into develop

TextGrid Aggregator Release 1.4.9

* switched preview mode to the new site
* support the sandbox in zip export
* fixed zipping search results that contain only filters, no query
* zip: streaming mode is true by default

pom.xml

@@ -5,7 +5,7 @@
         <modelVersion>4.0.0</modelVersion>
         <groupId>info.textgrid.services</groupId>
         <artifactId>aggregator</artifactId>
-        <version>1.4.9-SNAPSHOT</version>
+        <version>1.4.9</version>
         <packaging>war</packaging>
         <name>TextGrid Aggregator Service</name>