* remove loading backend in sse
* build mxnet in a second run
* a third run to fix everything
* fix docstring in sampler
* fix docstring in transformer
* README for doc build
* some reordering and printing
* use filename_pattern instead of ignore_pattern to reduce warning at the cost of redundant work...
* add env var to use mxnet in Jenkinsfile
* remove step 3, it's already fixed by previous commit