Initial compatibility tests.
Adds compat tests to travis.
Changes the build to only use CDH4.6 dependencies.
Comments out large thrift struct tests since they don't work with
parquet-1.2.5-cdh4.6.0
Changes parquet-tools version to 1.5.0.

Cloudera won't publish parquet-tools until CDH5.2 and we gave up trying
to persuade them after arguing with them for a week.
Adds Backward compatibility tests for parquet 1.2.5-cdh4.6.0.
Uses parquet-1.2.5-cdh4.6.0-p337.

This patch enables support for large thrift structs.
Enable large thrift struct tests.

This reverts commit 75726dd67cb09f8ae2a21985282483a2f26ede35.
Add backwards compatibility tests for parquet-1.2.5-cdh4.6.0-p337.