Add the repository of ts_rotator_controller.

Began to implement the Dockerfile for rotator PXI. Installed the linux kernel 3.18.25 but some setting of ".config" can not be applied. Therefore, I used the default config setting for linux kernel. I compared the ".config" file in github and M2 hexapod PXI machine and document. There is some inconsistency between the document and file.

Build the Xenomai dual kernel and library and EtherCAT. Worked on the documentation.

Push the build image to Docker hub:

https://hub.docker.com/repository/docker/lsstts/rotator_pxi

Updated the README.md of ts_rotator_controller and removed some library files.

Tried to compile the code in docker container.

Added the Jenkinsfile and pass the test:

https://tssw-ci.lsst.org/job/LSST_Telescope-and-Site/job/ts_rotator_controller/job/tickets%252FDM-23815/

The PRs:

1. https://github.com/lsst-ts/ts_Dockerfiles/pull/63

2. https://github.com/lsst-ts/ts_rotator_controller/pull/1

The Jenkins test is here:

https://tssw-ci.lsst.org/job/LSST_Telescope-and-Site/job/ts_rotator_controller/job/tickets%252FDM-23799/

Build the rotator PXI controller in docker container.

Reviewed in github. It looks good and it is great that you figured out how to build the code in a Docker image.