Installed neo4j-gremlin and still neo4j plugin not shown in the list

[root@master incubator-tinkerpop]# ./bin/gremlin.sh

\,,,/
(o o)
----oOOo(3)oOOo----
plugin activated: tinkerpop.server
plugin activated: tinkerpop.utilities
plugin activated: tinkerpop.tinkergraph
gremlin> g = Neo4jGraph.open('/tmp/neo4j')
No such property: Neo4jGraph for class: groovysh_evaluate
Display stack trace? [yN] N
gremlin> :plugin list
==>tinkerpop.server[active]
==>tinkerpop.gephi
==>tinkerpop.utilities[active]
==>tinkerpop.sugar
==>tinkerpop.tinkergraph[active]
gremlin> :install com.tinkerpop neo4j-gremlin 3.0.0.M7
Detected a non-standard Gremlin directory structure during install. Expecting a 'lib' directory sibling to 'ext'. This message does not necessarily imply failure, however the console requires a certain directory structure for proper execution. Altering that structure can lead to unexpected behavior.
==>Loaded: [com.tinkerpop, neo4j-gremlin, 3.0.0.M7]
gremlin> :plugin list
==>tinkerpop.server[active]
==>tinkerpop.gephi
==>tinkerpop.utilities[active]
==>tinkerpop.sugar
==>tinkerpop.tinkergraph[active]
gremlin> :plugin use tinkerpop.neo4j
==>tinkerpop.neo4j could not be found - use ':plugin list' to see available plugins
gremlin>