Prevent Matlab on OS X from crashing on error

Replace CHECK() and LOG(FATAL) with LOG(ERROR) and mexErrMsgTxt

A failed CHECK() or LOG(FATAL) causes Matlab to crash on OS X 10.9 with Matlab 2014a.
clean incorrect relu test code
relax benchmark milliseconds threshold
Merge pull request #1417 from Yangqing/dev

clean incorrect relu test code
fix relu cudnn test bug
Merge pull request #1432 from Yangqing/dev

fix relu cudnn test bug
fixed tanh to not return NaN for input values outside the range [-40, 40]
Fixed header order to satisfy linter
in SoftmaxLossLayer, check label >= 0 in addition to upper bound
use DCHECK in SoftmaxLossLayer so that bounds checking has no perf penalty without DEBUG
Merge pull request #1469 from longjon/label-lower-bound

Check both lower and upper bounds in SoftmaxLossLayer
Merge pull request #1455 from seanbell/tanh-fix

Fix tanh layer for badly scaled input values
remove redundant code in ConvolutionLayer::Reshape
Merge pull request #1505 from longjon/conv-dedup

Remove redundant code in ConvolutionLayer::Reshape
Better instructions for updating Homebrew after modifying formulae

Previous instructions glossed over how to deal with OpenCV-related update problems
Update mean file help

Numpy array dimensions should be [Channels x Height x Width], NOT [Height x Width x Channels]

If an image mean file is supplied with channels as the last dimension, classify.py throws errors like:

ValueError: operands could not be broadcast together with shapes (3,227,227) (256,0,225) (3,227,227)
clarify #endif comment
Merge pull request #1527 from drdan14/classify-py-mean-dims

Update mean file help
Merge pull request #1516 from drdan14/update-homebrew-install-instructions

Better instructions for updating Homebrew after modifying formulae
Merge pull request #1406 from CellScope/matcaffe-osx-fix-crash-on-error

Prevent Matlab on OS X from crashing on error