Fix license in info.xml - GPLv2 it is

Author: DeepDiver1975

appinfo/info.xml

@@ -4,7 +4,7 @@
     <name>Dropbox storage support</name>
     <description>Dropbox backend for files_external</description>
     <summary>This is storage app to mount Dropbox as an External Storage in ownCloud</summary>
-    <licence>GPL-2.0</licence>
+    <licence>GPLv2</licence>
     <author>Hemant Mann</author>
     <version>1.0.0</version>
     <category>storage</category>