Fix buck build when referring SNAPSHOT version

When referring to a maven SNAPSHOT version where the
version string contains an additional part, e.g. for a
company internal patch, buck incorrectly calculated the path: Buck
replaced everything after the first '-' of the version with
'-SNAPSHOT'. 

An example is
'gwtorm:gwtorm:1.8.0-sap-01-SNAPSHOT-20130927.083646-2'

Now we remove everything after '-SNAPSHOT'.

Change-Id: I8a200d46139bf476d7824469ee5a7380891ea46d
diff --git a/lib/maven.defs b/lib/maven.defs
index db37cdb..7049bfa 100644
--- a/lib/maven.defs
+++ b/lib/maven.defs
@@ -47,7 +47,7 @@
 
   if 'SNAPSHOT' in version:
     file_version = version.replace('-SNAPSHOT', '')
-    version = version.split('-')[0] + '-SNAPSHOT'
+    version = version.split('-SNAPSHOT')[0] + '-SNAPSHOT'
   else:
     file_version = version