Workaround for outlook, who doesn't like quoted-printable encoding

For example, outlook 2013 plus would not interpert the following html
(encoded via quoted-printable encoding):
<a href=3D=22http://engineering=
.como.com/ghost/signup/MTQxNTcwNzM5MTYwN3x5dXJ5QG5peC5jby5pbHx3NVBmUUN4RGZr=
cGhKc3FPOElybXNZNWtzR0FMTU9tRFI5UlNyRWQ4SGJZPQ=3D=3D/=22 style=3D=22color:
=

The workournd forces node-mailer to user base64, which outlook understands
well.
Faster dropdown animation for publish button

Closes #4390

- Apply same animation timing from the nav bar dropdown to the publish button dropdown
Cleanup User List styles

No issue

* Cleans up the Sass a bit
* Uses the same basic markup as other settings pages. Before, we had extra elements which required 'reseting'
Remove .eot & .ttf fonts

No issue

According to [caniuse](http://caniuse.com/#feat=woff), all the browsers we support (last 2 versions of major browsers) support the `.woff` font format. It's actually what pretty much all browsers will serve if its offered anyway.

This PR removes the .eot and .ttf font formats.

SVG remains as its the base file we use to add new icons & convert into other formats. It is not referenced anywhere.
full BREAD Tag endpoints and Tag api tests

close #4263
- implemented full BREAD Tag API
- deleting a tag will also detach its relations to posts
- tests of Tag API
Refactor component styles

Continues on from #4401

- Reformats the Sass to match our new style (property order, comments, & white space)
- Changes the modal container to a class from an ID (and adjust tests)
Merge pull request #4406 from RaoHai/tag-endpoints

full BREAD Tag endpoints and Tag api tests
Adds 'save' shortcut to settings screens
closes #4414
- adds `ctrl/cmd+s` shortcuts to `settings/general` screen
- adds `ctrl/cmd+s` shortcuts to `settings/user/xx` screen
- extracts `ctrlOrCmd` variable to separate module for reuse
Merge pull request #4438 from Gargol/4414

Adds 'save' shortcut to settings screens
Update contribution guidelines

ref #4396

- adds a TLDR, updates links throughout & improves language
Merge pull request #4447 from ErisDS/contrib-update

Update contribution guidelines
Merge pull request #4441 from PaulAdamDavis/cleanup-sass-components

Refactor component styles
Merge pull request #4433 from PaulAdamDavis/rm-ttf-eot-fonts

Remove .eot & .ttf fonts
Merge pull request #4391 from PaulAdamDavis/publish-transition

Faster dropdown animation for publish button
Merge pull request #4397 from PaulAdamDavis/cleanup-users

Cleanup User List styles
Enable .fade-out animations in Safari

Closes #4432

Random sidenote: Safari is a whiny non-animating wuss and figuring this
out took way longer than one would think.
Fix post tags input.

Closes #4378. Closes #4455.
- Trim whitespace from tag names on entry.
- Prevent duplicate tags in suggestion list.
- Fix unhandled exception that happens when backspace is pressed in
  an empty tags input box.
Merge pull request #4456 from felixrieseberg/iss4432

Enable .fade-out animations in Safari
Merge pull request #4457 from jaswilli/tags

Fix post tags input.
Update showdown to showdown-ghost 0.3.4

closes #2675

- update showdown to the newly published showdown-ghost module which has a fix for the lack of language support in codeblocks