Allow use of core.commentchar when creating git commit message

Fixes #81
Adding use of commentchar config and edit changelog
# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
#
# On branch jwhitcraft-master
# Changes to be committed:
# 	modified:   Changelog.md
# 	modified:   lib/models/git-commit.coffee
Prepare 3.6.1 release
Update Changelog.md
Fix: git.relativize to working repository

The problem I fixed inside git.relativize occurs when user opens a
project folder, which is not directly a root folder, but rather a
subfolder inside repository.
I have left atom.project.relativize there, might be redundant because
the user will always have a repository if they wish to use git.
Merge pull request #86 from markogresak/master

Fix: git.relativize to working repository
Update changelog
Prepare 3.6.2 release
Fixes #87 and Fixes #88
Prepare 3.7.0 release
Implement the `git stash` command.

`git stash save` = Stash: Save Changes
`git stash pop` = Stash: Apply (Pop)
`git stash apply` = Stash: Apply (Keep)
`git stash drop` = Stash: Delete
Add 'Drop' to Git Stash Delete in command menu
Merge branch 'git-stash'
Update Changelog.md
Prepare 3.8.0 release
Fixes #61
Prepare 3.9.0 release
Pull lists remotes
Prepare 3.10.0 release
Fixes #89