Merge pull request #2 from sabof/master

Narrowed icons to 8px
Add customize variable for position of fringe
Update README and add screenshots
Bumpup version and add Changes
fix screenshot pathes
Add initialize function for specified initialize
Bump version and requirement package version

And update Changes.
Improve deleting overlays

And update requirements version
Fix minimum supported Emacs version
Update requirement package version
update screenshot
Add explanation for working with linum-mode
Update requirement package version
Update explanation of customization
Update requirements package version.

Because some bugs of git-gutter.el is fixed
Update required package version for fixing bug
Add explanation of 'git-gutter-fringe' installation
Remove byte compiling error of fringe-helper

Because it is fixed at latest version.
improved overlay deletion