Sagemaker-mxnet-inference

Bug fixes and other changes

* build context in release build
* make consistent build context for py versions
* Revert "Update build context on 1.4.1 EI dockerfiles (64)"
* a typo in build_all script
* Update build context on 1.4.1 EI dockerfiles
* correct typo in buildspec
* enable PR build
* separate pip upgrade from other installs
* New py2 dlc dockerfiles
* New py3 dlc dockerfiles

Documentation changes

* Update the build instructions to match reality.

Bug fixes and other changes

* retry mms until it's ready

Bug fixes and other changes

* split cpu and gpu tests for deployments in buildspec-release.yml
* add missing placeholder in test for non-eia test command.

Bug fixes and other changes

* fix flake8
* update no-p2 regions and no-p3 regions.
* Skipping EIA test if accelerator type is None.

Features

* add MXNet 1.4.1 Dockerfiles

Bug fixes and other changes

* use Python 2 build logic for EI images during release
* add missing files needed for building MXNet 1.4.1 Python 2 images
* configure flake8 to ignore the docker/ directory