Changelogs for version 2.0.0
Bump version in `bin/git-extras`

- Bump version to 2.0.0 in `bin/git-extras` to enable updating package
via `git-extras update`
Merge pull request #255 from sanusart/master

Bump version in `bin/git-extras`.
use mixin to add 'is git repo' check for some commands

When those commands are used outside a git repo, 'Not a git repo!' will be
printed to stderr
Merge pull request #258 from spacewander/master

use mixin to add 'is git repo' check.