Add a CHANGELOG.md file to track breaking changes and new features in the GDK.

Fixes #152.

See merge request !194

Use https where possible in docs/comments



See merge request !193

Fix installation link

Fixed installation link.

See merge request !192

Fix spelling of 'instructions' on GDK README.

It's much more fun to say 'instructinos', unfortunately.

See merge request !190

```
[ruben@mbp ~/projects/gdk-ce (master *)]$ gdk reconfigure
(in /Users/ruben/projects/gdk-ce)
rm -f \
            gitlab/config/gitlab.yml \
            gitlab/config/database.yml \
            gitlab/config/unicorn.rb \
            gitlab/config/resque.yml \
            gitlab-shell/config.yml \
            redis/redis.conf \
            Procfile
sed -e "s|/home/git|/Users/ruben/projects/gdk-ce|"\
             gitlab/config/gitlab.yml.example > gitlab/config/gitlab.yml
port= support/edit-gitlab.yml gitlab/config/gitlab.yml
  gitlab_shell:
sed "s|/home/git|/Users/ruben/projects/gdk-ce|" database.yml.example > gitlab/config/database.yml
cp gitlab/config/unicorn.rb.example.development gitlab/config/unicorn.rb
echo "listen '/Users/ruben/projects/gdk-ce/gitlab.socket'" >> gitlab/config/unicorn.rb
sed "s|/home/git|/Users/ruben/projects/gdk-ce|" redis/resque.yml.example > gitlab/config/resque.yml
command -v bundler > /dev/null || gem install bundler
sed -e "s|/home/git|/Users/ruben/projects/gdk-ce|"\
              -e "s|^gitlab_url:.*|gitlab_url: http+unix://%2FUsers%2Fruben%2Fprojects%2Fgdk-ce%2Fgitlab.socket|"\
              -e "s|/usr/bin/redis-cli|/usr/local/bin/redis-cli|"\
              -e "s|^  socket: .*|  socket: /Users/ruben/projects/gdk-ce/redis/redis.socket|"\
              gitlab-shell/config.yml.example > gitlab-shell/config.yml
GOPATH=/Users/ruben/projects/gdk-ce/gitlab-workhorse go install gitlab.com/gitlab-org/gitlab-workhorse/...
ln -s /Users/ruben/projects/gdk-ce/gitlab/.ruby-version .ruby-version
ln: .ruby-version: File exists
make: *** [.ruby-version] Error 1
```

Fix links in doc/vagrant.md



See merge request !189

Allow workhorse to start when PATH contains whitespace



See merge request !188

Fix links

Needed to add `blob/master/` to links to CLA's.

See merge request !187

Document how to delete a non-existing migration



See merge request !185

 Conflicts:
	README.md

Create gitlab/public/uploads

This was an oversight in the Makefile. Most of the time some piece of
application code would make the directory anyway with `mkdir -p` but
we should do it eagerly, not lazily.

See merge request !184

This was an oversight in the Makefile. Most of the time some piece of
application code would make the directory anyway with `mkdir -p` but
we should do it eagerly, not lazily.

Refer back to GitLab CE's CONTRIBUTING.md file




See merge request !183

Updated prepare.md with new phantomjs version (2.1.1)



See merge request !182

No longer need to set PATH for workhorse development

No longer needed because of:

https://gitlab.com/gitlab-org/gitlab-workhorse/merge_requests/57

See merge request !181

Add docs about overriding host with host file

This MR adds a note to `set-up-gdk.md` about using `./host` file to override host the workhorse process will bind to.

This is especially useful when someone uses GDK inside the Docker container and wants to expose Workhorse.

See merge request !180

Small refactor of set-up-gdk.md



See merge request !179

Update documentation to use Ruby 2.3.1

GitLab is using Ruby 2.3.1 now on master, I figure the documentation should also be updated.

See https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4948

cc: @zj @jacobvosmaer-gitlab 

See merge request !178