Merge Python3 breaking changes from V2 to master

[rmkeezer]

And ensure that the commit message is semantic release friendly for a breaking change 👍

[codecov]

Codecov Report

Merging #68 into master will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #68      +/-   ##
==========================================
+ Coverage   97.88%   97.89%   +0.01%     
==========================================
  Files          17       17              
  Lines         616      619       +3     
==========================================
+ Hits          603      606       +3     
  Misses         13       13              

Impacted Files	Coverage Δ
ibm_cloud_sdk_core/api_exception.py	100.00% <100.00%> (ø)
ibm_cloud_sdk_core/authenticators/authenticator.py	75.00% <100.00%> (ø)
...oud_sdk_core/authenticators/basic_authenticator.py	100.00% <100.00%> (ø)
..._core/authenticators/bearer_token_authenticator.py	100.00% <100.00%> (ø)
...loud_sdk_core/authenticators/cp4d_authenticator.py	100.00% <100.00%> (ø)
...cloud_sdk_core/authenticators/iam_authenticator.py	96.66% <100.00%> (ø)
...d_sdk_core/authenticators/no_auth_authenticator.py	100.00% <100.00%> (ø)
ibm_cloud_sdk_core/base_service.py	93.87% <100.00%> (+0.04%)	⬆️
ibm_cloud_sdk_core/cp4d_token_manager.py	100.00% <100.00%> (ø)
ibm_cloud_sdk_core/detailed_response.py	100.00% <100.00%> (ø)
... and 4 more

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[mkistler]

If this PR is going to drop support for Python 2.7, you need to update the README. Also, I recommend stating Python 3.5.3 as the minimum Python version, as this is the version needed by aiohttp, and we'd like to have the option to use aiohttp for async requests without another major release of the Python core.

[padamstx]

Before we can merge the v2 branch into master, we'll need to do these things:

1. Do a rebase on the current master branch since this PR thinks the v2 branch is out of date.
2. Make sure that each of the commit messages in the v2 branch are correct. i.e. whichever commits represent breaking changes should have the appropriate "BREAKING CHANGE" mesage.

For #2, this might be all of the commits, in which case we could do this:

1. create a new "v2" branch, maybe call it "v2-new".
2. one at a time, and in the same order as the commits appear in the "v2" branch, cherry-pick a commit from "v2" into "v2-new", then run git commit --amend to modify the commit message so that it properly reflects a breaking change.
3. when each commit from "v2" has been handled in step 2, you could remove your local "v2" branch, then rename "v2-new" to be "v2", then run git push -f to update in place the "v2" branch (i.e. your PR).
4. after the build is clean, etc. the updated "v2" branch can be merged into master.

[padamstx]

Looks good, and the commit messages appear to be fine.

Here's a suggestion for how to fully test this PR once it is merged into master:

1. when this PR is merged into master, it will cause v2.0.0 of the python core to be created
2. we have an open issue to add a system test stage to each template repository, so I'd like to suggest that you add the python system test stage to the python-sdk-template repo (.travis.yml), and update that template repo to require v2.0.0 of the python core (requirements.txt).
3. when you submit your PR for feat(core): Add semantic release #2, the pr and push builds for that should run a python system test that incorporates the latest master-branch generator, along with your changes in the python-sdk-template repo which by extension will now use the new v2.0.0 of the core.

[ibm-devx-automation]

🎉 This PR is included in version 2.0.0 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀