Remove java related parts from parquet-format

还没有人认领这个 Issue。

Since the java code generation part has moved to parquet-mr there is no reason (and it is misleading) to still keep these java files in the parquet-format repo and to release in a jar format.
The proposal is the following:
- Remove java code from the repository and update the pom.xml accordingly
- Keep the unit tests (to validate the PRs) but don't include them in the release. (We might release a separate `-tests` jar.)
- Release in a zip format instead of a jar. The zip would contain all the documentation and the `parquet.thrift` file
- Also move the [dremel paper](https://github.com/apache/parquet-mr/tree/master/doc/dremel_paper) from parquet-mr to parquet-format
- Update the [How to release](http://parquet.apache.org/documentation/how-to-release/) doc

**Reporter**: [Gabor Szadovszky](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=gszadovszky) / @gszadovszky
**Assignee**: [Gabor Szadovszky](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=gszadovszky) / @gszadovszky

_{**Note**: *This issue was originally created as [PARQUET-2007](https://issues.apache.org/jira/browse/PARQUET-2007). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

首先检查仓库中的 Java 源代码和 pom.xml，然后查看现有的单元测试和发布配置。检查 parquet.thrift 文件、parquet-mr 中的 dremel_paper 位置以及 How to release 文档；当仓库和发布内容与所列提案一致，且主发布中没有 Java 构件时，即表示完成。

由索引模型根据 Issue 内容生成。