Update .workspace class with custom element

Because of the update with the custom elements, i noticed that `.workspace` hasn't been updated in the `keymap.cson`, but `.editor` has (to `atom-text-editor`).
Dispose of ::scopedConfigSubscriptions when DisplayBuffer is destroyed
Dispose of ::scopedConfigSubscriptions when Editor is destroyed
Merge pull request #4087 from philipgiuliani/patch-1

:memo: Update .workspace class with custom element
Add padding to panel headings
Add more relevant (but contrived) example in init.coffee.

Closes #4089
Prepare 0.144
Merge branch 'master' of github.com:atom/atom
:arrow_up: language-python@0.23
:arrow_up: language-css@0.22
Upgrade git-diff to use atom-text-editor
:arrow_up: language-sass@0.25
Fully fetch draft release

Assets in a bad state aren't returned from the releases listing
endpoint.
Upgrade bookmarks to work with shadow dom
Upgrade find-and-replace to use atom-text-editor
:arrow_up: settings-view@0.156
Fetch draft assets from assets URL

This will include assets in a bad state that should still be deleted
and aren't returned from the main release URL.
:arrow_up: language-shellscript@0.10
Render all stylesheets in atom-styles elements without contexts

Signed-off-by: Nathan Sobo <nathan@github.com>
W/o shadow-dom, don't add global atom-styles element for text editor

Signed-off-by: Nathan Sobo <nathan@github.com>