Add Github issue template to curb misuse.

For information on Github issue templates, see:
https://github.com/blog/2111-issue-and-pull-request-templates

The template has been revised according to discussion with @shelhamer
and @willyd on pull request BVLC#4914.

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,19 @@
+Please use the [caffe-users list](https://groups.google.com/forum/#!forum/caffe-users) for usage, installation, or modeling questions, or other requests for help.
+_Do not post such requests to Issues._ Doing so interferes with the development of Caffe.
+
+Please read the [guidelines for contributing](https://github.com/BVLC/caffe/blob/master/CONTRIBUTING.md) before submitting this issue.
+
+### Issue summary
+
+
+### Steps to reproduce
+
+If you are having difficulty building Caffe or training a model, please ask the caffe-users mailing list. If you are reporting a build error that seems to be due to a bug in Caffe, please attach your build configuration (either Makefile.config or CMakeCache.txt) and the output of the make (or cmake) command.
+
+### Your system configuration
+Operating system:
+Compiler:
+CUDA version (if applicable):
+CUDNN version (if applicable):
+BLAS:
+Python or MATLAB version (for pycaffe and matcaffe respectively):