Update the tinkerpop.version property.

Author: spmallette

pom.xml

@@ -49,7 +49,7 @@
         <module>gremlin-groovy</module>
     </modules>
     <properties>
-        <tinkerpop.version>2.6.0</tinkerpop.version>
+        <tinkerpop.version>2.7.0-SNAPSHOT</tinkerpop.version>
         <junit.version>4.5</junit.version>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     </properties>