Added support for function deployment from gzip/bzip2/xz compressed tar files

[varunbpatil]

Issue Ref: #1167

Description:
Added support for deploying and updating functions from gzip/bzip2/xz compressed tar files.
Supports the following standard file extensions - .tar.gz, .taz, .tgz, .tar.bz2, .tb2, .tbz, .tbz2, .tz2, .tar.xz

TODOs:

• Ready to review
• Automated Tests
• Docs

[andresmgot]

Good work @varunbpatil, nice test coverage :) For the changes in the unzip image to take effect, you need to update the image reference in the manifest (kubeless-non-rbac.jsonnet). I have built the image with your changes, replace it to be able to run your tests: kubeless/unzip@sha256:e867f9b366ffb1a25f14baf83438db426ced4f7add56137b7300d32507229b5a)

[varunbpatil]

Thanks @andresmgot :) In order to run the url+compressedtar tests from examples/Makefile, I also need the compressed tar's to be present in the examples folder already. Do you want me to create a separate PR for just those 3 files?

Edit: I have parameterized the URLs in examples/Makefile to use the commit SHA1 from Circle CI so that we can refer to files created in the current PR instead of the files from master branch. I have also fixed the prevailing CI failure in get-python-metadata. CI is passing with these changes.

[andresmgot]

Great, thanks for the changes!