[java] implement Dictionary vector

[asfimport]

Reporter: Julien Le Dem / @julienledem
Assignee: Emilio Lahr-Vivaz / @elahrvivaz

Related issues:

• [C++] Implement dictionary-encoded array container (is related to)

_{Note: This issue was originally created as ARROW-366. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 309
#309