PARQUET-12: Add format support for additional converted types.

Author: Jacques Nadeau <jacques@apache.org>

Closes #3 from jacques-n/PARQUET-12 and squashes the following commits:

7001502 [Jacques Nadeau] Remove micros implementations until everyone is agreed on micros versus nanos.
b0e067c [Jacques Nadeau] PARQUET-12: Add format support for additional converted types.
PARQUET-58: Add PR merge tool

This is a copy of the merge tool from incubator-parquet-mr. I've used it to merge a PR already, so it works.

Author: Ryan Blue <rblue@cloudera.com>

Closes #4 from rdblue/PARQUET-58-add-merge-tool and squashes the following commits:

b06c32c [Ryan Blue] PARQUET-58: Add PR merge tool and docs.
PARQUET-12: Add specs for new logical types.

This adds the new logical types from #3 to the LogicalTypes.md specification.

Author: Ryan Blue <rblue@cloudera.com>

Closes #5 from rdblue/PARQUET-12-add-new-type-docs and squashes the following commits:

be414fe [Ryan Blue] PARQUET-12: Add specs for new logical types.
Add anchor links

I'm starting work on a Haskell implementation of the Parquet format and wanted to get up to speed on the various encodings used.

I find that the current Encodings.md document is quite confusing.

This is a first pass at some clean-up.

There were multiple references in the text that made no sense, as they were references to sections which appear to have been re-ordered in the document.

I've rewritten those references as anchor links within the document to avoid future issues.

Author: Chris Heller <hellertime@gmail.com>
Author: Chris Heller <cheller@akamai.com>

Closes #1 from hellertime/feature/improve-encoding-doc and squashes the following commits:

c2e5f54 [Chris Heller] Link the delta encoding section
c1e85d2 [Chris Heller] Add anchor links
PARQUET-11: Reduce memory pressure when reading footers

based on https://github.com/apache/incubator-parquet-format/pull/2

Author: julien <julien@twitter.com>
Author: Dmitriy Ryaboy <dvryaboy@gmail.com>

Closes #7 from julienledem/reduce_metadata_memory and squashes the following commits:

96ff408 [julien] Merge branch 'master' into reduce_metadata_memory
1c382cc [julien] implement delegate instead
7664919 [Dmitriy Ryaboy] intern parquet metadata strings when reading them