Lock the mex file to avoid Matlab crashes.

Commands like "clear all" and "clear function" causes segmentation faults or errors like these (especially after an 'init'):
 libprotobuf ERROR google/protobuf/descriptor_database.cc:57] File already exists in database: caffe/proto/caffe.proto
 libprotobuf FATAL google/protobuf/descriptor.cc:862] CHECK failed: generated_database_->Add(encoded_file_descriptor, size):
 [libprotobuf ERROR google/protobuf/message.cc:333] Type appears to be in generated pool but wasn't registered: caffe.LayerParameter
 Attempt to restart MATLAB?
To avoid these, lock the the mex file.
Ignore LevelDB files
Explain how to fix homebrew to allow updates after editing formulae
Merge pull request #1001 from drdan14/homebrew-git-repair

  Explain how to fix homebrew to allow updates after editing formulae
[docs] Several documentation fixes

- Fix a typo and a path in MNIST tutorial
- Rework instructions about Fedora installation
Merge pull request #997 from ozancaglayn/dev

  [docs] Several documentation fixes
back-merge

  [docs] Several documentation fixes
  Explain how to fix homebrew to allow updates after editing formulae
Fix norm_region param in cifar10 deployment net
patch MacOS NVCC boost::thread issue
xcode compiler complaints (warnings)...
Merge pull request #1011 from YS-L/dev

Fix norm_region param in cifar10 deployment net
fix data_transformer param_name
[docs] new PR policy: send master fixes + docs to master

To address fixes and documentation updates to master between official
releases from `dev` to `master` PRs will be accepted to `master`.

All new development must still branch off and PR to `dev`.
Merge pull request #1012 from shelhamer/pr-policy

new PR policy: send master fixes + docs to master
renaming && typo fix
fix up renaming
Makefile: fix boost::thread linking, drop pthread, sort
Merge pull request #1010 from qipeng/boost-thread-with-nvcc

Fix boost-CUDA trouble in OS X build.
fix up leveldb ignore
Merge pull request #1004 from kloudkl/ignore

Ignore leveldb more thoroughly