Remove calling git-gutter after revert(#30)

Because git-gutter is called after calling save-buffer
[PATCH 03/15] Restore window config after revert-hunk(#30)
[PATCH 04/15] Add `clear-diff-infos' as the default clear-function

Remove default call to `remove-overlays' which is not needed for git-gutter-fringe
[PATCH 09/15] [Refactor] Extract function `git-gutter:show-gutter'(#30)
Merge branch 'test'
Bump up 0.45 and update Changes
Use relative path if system is Windows(#30)

Cygwin can't handle Windows absolute path(Case: Mingw Emacs + Cygwin git).
Other platform uses absolute path instead of relative path, because
git command is failed if git repository place in symbol link path.
Bump up 0.46 and update Changes