Recommend Win32 version 0.45

It was on this version that the Win32::GetConsoleOutputCP was
implemented.
Specify depedency on Gerrit::REST version 0.005

This version fixed a bug that rendered git-gerrit unusable.
Implement 'push' --submit option

This tells Gerrit to auto-merge the change during the push, which is a
feature implemented in Gerrit 2.7.
Implement 'push' --base option

This tells Gerrit to select a new merge base during the push, which is
a feature implemented in Gerrit 2.7.
Fix documentation
Implement git-gerrit.reviewers configuration

Through this configuration variable it's now possible to specify
default reviewers based on the branch to which one pushes and also on
the files being changed.
v0.012

  [New features]
  - Implement the git-gerrit.reviewers configuration variable through
    which it's now possible to specify default reviewers based on the
    branch to which one pushes and also on the files being changed.

  - Implement option 'git gerrit push --submit' to tell Gerrit to
    auto-merge the change during the push, which is a feature
    implemented in Gerrit 2.7.

  - Implement option 'git gerrit push --base=BASE' to tell Gerrit to
    select a new merge base during the push, which is a feature
    implemented in Gerrit 2.7.

  [Fixes]
  - Require minimum versions of Gerrit::REST and Win32.