* Add cpplint_pre_commit.hook

* Update hook

* Disable dropout_op_test.cc

* Remove cpplint.py but requires users to install their version

* fix cpplint error

smaller binary proto
avoid untrackable kernel

I expect that we need it to:
1. Find flaky test commit.
2. Find regression commit.
Disable test is dangerous. We should first try to find the culprit commit
and fix it or revert it.

I managed to find 3d1ac72a (between 279aa626 and 67731297) that causes
the recent failure of test_rnn_encoder_decoder.

* append cmd in manylinux dockerfile.x86

* add new line

* "fix decode bug"

* "follow commnet"

* "fix error"

* "fix hook bug"

* fix based comment

* fix copyright

* fix based on comment