gitdb and gitdb2 on PyPI

[Harmon758]

In 2015, access was lost to the PyPI account that owns gitdb.
v0.6.4 was the last release under the gitdb package on PyPI prior to this happening.

In 2016, gitdb2 was created to continue development for the library under a new package (38866bc), and every release since then has been with that package name. This has caused confusion (see #45, #47, #57, gitpython-developers/GitPython#983) and having an old, stale PyPI project is less than ideal.

Recently, the original PyPI account has been recovered.
The intention now is to transition back to using the original gitdb package name and have the gitdb2 package simply be a mirror/dummy package that depends on and installs gitdb, so as to maintain backwards compatibility.

Currently, these are the anticipated steps that need to be taken:

• Release a new version, v3.0.3, as the gitdb2 package, that restricts the smmap2 version to < 3
  (See smmap and smmap2 on PyPI smmap#44)
• Release a new version, v4.0.0, as the gitdb package; the only change from gitdb2 v3.0.3 should be to require smmap rather than smmap2 (smmap and smmap2 on PyPI smmap#44)
• Create a gitdb2 branch with a single setup.py that requires gitdb
• Release a new version, v4.0.0, of the gitdb2 package from the gitdb2 branch
  • Note Because I (@Byron) accidentally released step 2 in this list as package gitdb2 instead of gitdb, v4.0.0 of gitdb2 already existed. The change requested here is now in v4.0.1.

v4.0.0 for both packages should be functionally equivalent to gitdb2 v3.0.3, with gitdb2 v4.0.0 simply installing gitdb >= 4.0.0 and with gitdb v4.0.0 requiring smmap rather than smmap2 (gitpython-developers/smmap#44).

• gitdb2 v3.0.3 was released with an erroneous and incomplete changelog
  gitdb2 v3.0.3.post1 has been tagged and released on PyPI to fix this
• gitdb v4.0.0 was tagged with the wrong package name and released with an incomplete changelog and unbound smmap requirement version specifiers
  The master branch has been force-pushed to 253dfe7 and gitdb v4.0.1 has been tagged and released on PyPI
  • gitdb v4.0.0 has been deleted on PyPI
• gitdb2 improperly branches off of the 4.0.0 tag and includes the entire GitDB library
  The gitdb2 branch has been force-pushed to d3bf396 to be properly set up for gitdb2 to be a mirror package and the gitdb2-4.0.0 and gitdb2-4.0.1 tags have been deleted
• gitdb2 v4.0.0 was released as the entire GitDB library and without requiring gitdb
  gitdb2 v4.0.0 has been deleted on PyPI
• gitdb2 v4.0.1 was released as the entire GitDB library while still requiring gitdb
  gitdb2 v4.0.2 has been released on PyPI from the new gitdb2 branch (d3bf396)
  • gitdb2 v4.0.1 has been deleted on PyPI
• A new version of GitPython, v3.1.0, that requires gitdb rather than gitdb2, has been tagged (at first, gitpython-developers/GitPython@c859019 was tagged, but that commit forgot the version bump and as such, it has now been re-tagged to the version bump commit, gitpython-developers/GitPython@8c9da73) and released on PyPI

gitdb v4.0.1 and gitdb2 v4.0.2 should be functionally equivalent to gitdb2 v3.0.3 with gitdb v4.0.2 simply installing gitdb >= 4.0.1 and with gitdb v4.0.1 requiring smmap rather than smmap2 (gitpython-developers/smmap#44).

Note: @Byron was having issues with releases, so I was added as a maintainer for gitdb, gitdb2, smmap, and smmap2 on PyPI. Since there were already issues with the new signature key being used, I've released gitdb v4.0.1, gitdb2 v3.0.3.post1, gitdb2 v4.0.2, smmap v3.0.1, and smmap2 v3.0.1 without any signature keys. The intention is still for @Byron to release new versions with the proper signature key once he has access to it again.