Bump version to 1.4.0-SNAPSHOT

Author: mwilliamson

pom.xml

@@ -2,7 +2,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>org.zwobble.mammoth</groupId>
   <artifactId>mammoth</artifactId>
-  <version>1.4.0</version>
+  <version>1.4.0-SNAPSHOT</version>
   <packaging>jar</packaging>
   <name>Mammoth</name>
   <description>Convert Word documents to simple and clean HTML</description>