Fix cmake build

* Use dedicated Dockerflie.cmake for cmake: Ensure cmake version >=3.5.
* Let cmake build protobuf 3.0.0-beta-2 from source. Version 3.0.0 cannot be used a.t.m. due to an integer type issue.
* Fix a bug in tf_models.cmake.
* Perform parallel make based on the number of cores.

New build command:

tensorflow/tools/ci_build/ci_build.sh cmake
tensorflow/tools/ci_build/builds/cmake.sh