Update fedora.spec for python2 and python3 handling

[nkadel]

Fedora and RHEL have split python packages in to "python2" and "python3 packages. Split up builds and packages accordingly to create distinct packages.
Activate "Suggests:" only for RHEL or Fedora with dnf enabled.
Do not build python2 packages on Fedora > 28, or python3 packages on RHEL 7 or less.
Rename scripts for python2 to "script2", for python3 to "script3".

[mcepl]

@nkadel what's wrong with python3 packages for RHEL-7 (considering there is EPEL7 which contains python3* package)?

[nkadel]

The EPEL package are incomplete and unreliable for general compilation of python modules, from my limited testing with them.

[nkadel]

The EPEL 7, python36 packages are now much more reliable for py2pack python3 compilation. But the fedora.spec needs to support it.

[crunchyjohn]

I'd be very interested if this issue could be revisited. With python2 hitting end of life, it would be great to have python3 support in the fedora specfile. This solution works, but I'd be equally happy with removing the python2 support and just having python3 be the default from here on out. Please let me know if there's any way I can help.

[nkadel]

This has been languishing, I never got the tests to all passy consistently as upstream updated. Feel free to branch and take a look at it. I might have a few patches. Sadly, I'e never personally gotten all the dependency reporting to consistently sort out the many different ways distinct pypi packages report or handle dependencies, so it's not a complete solution. And at this point, frankly, I'd prefer to set "%global with_python2 0" for all environments, now that RHEL 7 supports a built-in version of python3

[mcepl]

@nkadel What do you suggest to do with this and #117? Should we close it or rebase on the top of the current master?