(livingsocial@e62d859) Added support flattened versions of nested columns.

Summary:
For example, if I have a JSON record that looks like this:

{
  "address": {
     "city": "Baltimore"
  },
  "phone_number": "301-555-2525"
}

I can define Hive columns that look this:
CREATE TABLE json_test (
           address_city string,
           phone_number string,
) ROW FORMAT SERDE 'org.openx.data.jsonserde.JsonSerDe'
STORED AS TEXTFILE;

and a SELECT query would return the following:

hive> SELECT * FROM json_test;
OK
Baltimore 301-555-2525
Time taken: 0.432 seconds

Fixes T9270

Test Plan: `mvn package`, + @jamesgreenhill

Reviewers: JamesGreenhill, jeff

Subscribers: JamesGreenhill

Maniphest Tasks: T9270

Differential Revision: http://phabricator.local.disqus.net/D12992