[GPU-Plugin] Add basic continuous integration for GPU plugin. (#2431)

tests/ci_build/test_gpu.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+
+mkdir build
+cd build
+cmake .. -DPLUGIN_UPDATER_GPU=ON
+make
+cd ..
+cd python-package
+python setup.py install --user
+cd ../plugin/updater_gpu
+python -m nose test/python