pip install from repository

[khnazaretyan]

As we don't have all dependencies in PyPI, this enables users to install the package directly from repository using pip. References the issues #38 and #161.
It was tested with both Python2 and Python3 on CentOS and Photon containers, Mac OS X and Windows 10. Test results are posted in discussion of #38.

Requires newer version of setuptools.

After merging it should be possible to install the package with the following commands.

pip install --upgrade pip setuptools
pip install --upgrade git+https://github.com/vmware/vsphere-automation-sdk-python.git

The line git+https://github.com/vmware/vsphere-automation-sdk-python.git could also be added to requirements.txt and installed along with other requirements.

Notes

• setup.py should be maintained accordingly, in case the names of the WHL files in lib folder are modified. It might be accomplished by tagging the changes and modifying setup.py accordingly or by removing the versions from names of whls in under ./lib and keep the versioning in using git tags.
• When the dependencies will be in PyPI, this setup.py can be easily modified to install all dependencies from there.
• This setup.py is not 100% PEP8 compatible. Splitting URLs makes the dependencies + urls hard to read and understand. It'll be changed, in case no exception is allowed for setup.py.

[vmwclabot]

@khnazaretyan, you must sign every commit in this pull request acknowledging our Developer Certificate of Origin before your changes are merged. This can be done by adding Signed-off-by: John Doe <john.doe@email.org> to the last line of each Git commit message. The e-mail address used to sign must match the e-mail address of the Git author. Click here to view the Developer Certificate of Origin agreement.

• Commit 8238b6c must be signed by nkhachatur@gmail.com

[timblaktu]

@khnazaretyan it appears that this doesn't work, could you take a quick look at the problem I'm having in #259 ?