PARQUET-450: Fix several typos in Parquet format documentation
PARQUET-450: Fix several typos in Parquet format documentation

It also changes parquet.thrift location to conform to maven layout and add a link to it from README.md

Author: Laurent Goujon <lgoujon@twitter.com>

Closes #36 from laurentgo/update-format-specification and squashes the following commits:

244c119 [Laurent Goujon] Fix several typos/errors in Parquet documentation
90a2be4 [Laurent Goujon] Fix thrift source path to match maven layout

HyukjinKwon/parquet-mr-1,HyukjinKwon/parquet-mr,SinghAsDev/parquet-mr,laurentgo/parquet-mr,HyukjinKwon/parquet-mr-1,HyukjinKwon/parquet-mr,SinghAsDev/parquet-mr,apache/parquet-mr,HyukjinKwon/parquet-mr,apache/parquet-mr,apache/parquet-mr,HyukjinKwon/parquet-mr-1,laurentgo/parquet-mr,SinghAsDev/parquet-mr,laurentgo/parquet-mr