caffe --version should print the version/git hash

[berleon]

caffe does not print its version.
Current behaviour:

$ caffe --version
caffe

The expected behaviour would be to print the git hash.

$ caffe --version
caffe version rc2-470-g6a5425f

This issue can be resolved by setting gflags::SetVersionString.
The git hash can be obtained by git describe --tags. See this stackoverflow question for greater
detail: http://stackoverflow.com/questions/1435953/how-can-i-pass-git-sha1-to-compiler-as-definition-using-cmake

[lukeyeager]

👍

FYI, the CMake build already grabs this information, so it should be relatively easy to add:

https://github.com/BVLC/caffe/blob/0dfc5dac3d/cmake/Summary.cmake#L58-L76

[shelhamer]

Mostly done in #3311 although the full git describe output is not yet included.