Make GCS optional

[adriangonz]

Fixes #1018.

Changelog

• Import tests on Storage.py from KFserving.
• Move google-cloud-storage to extras_require under the gcs key.
• Rename tf_helper.py to imports_helper.py.
• Add new all key to extras_require which will install all the optional dependencies.
• Add CI tests for seldon_core[gcs] and seldon_core[all].

[adriangonz]

/uncc @gipster @gsunner
/cc @jklaise @axsaucedo @cliveseldon

[axsaucedo]

/ok-to-test

[axsaucedo]

/test this

[axsaucedo]

/test this

[adriangonz]

The linter will get fixed once #1020 is merged and this PR gets rebased.

[axsaucedo]

/test lint

[axsaucedo]

Just needs rebase, but looks good. I think having this as optional will not be as intuitive, so we'll have to make sure we are able to come up with a unified way to cover it through #885.

[axsaucedo]

It seems that Azure released an update that pushed their version 2.x into 12.x which apparently is breaking due to the version being bigger. Might be worth adding this fix to this PR:

[axsaucedo]

This is the bump in versions - crazy

[axsaucedo]

This basically adds to the point we were discussing - maintaining a library that keeps in sync with all the changes across these cloud libraries may become increasingly complex. Really interesting with the timing!

[adriangonz]

Fixes #1023

[axsaucedo]

/test integration

[axsaucedo]

/test integration

[seldondev]

@adriangonz: The following test failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
integration	fb8612c	link	/test integration

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.

[adriangonz]

/approve

[adriangonz]

/lgtm

[seldondev]

@adriangonz: you cannot LGTM your own PR.

In response to this:

/lgtm

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[seldondev]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: adriangonz

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [adriangonz]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment