Static integration of the new PSM

Reference #3932

Take this, and make it work.
Enlarge mobile matchMedia max-width

Closes #3941

It now matches the mobile MQ in CSS - https://github.com/TryGhost/Ghost/blob/master/core/client/assets/sass/components/navigation.scss#L163
Bumping version to 0.5.2-1

no ref
- because Hannah said "someone"
Merge pull request #3935 from PaulAdamDavis/new-psm

[WIP] New post settings menu
Merge pull request #3943 from halfdan/patch-2

Bumping version to 0.5.2-1
`grunt dev` calls default task

Closes #3942
`js-` prefix; fix content preview back button

Closes #1990, Ref #3810
- Add `js-` prefix to jQuery calls throughout code and templates
- move MarkdownComponent classNames to template
- Fix back button on posts content preview
- Remove dead code for preview tabbing jQuery
Merge pull request #3946 from novaugust/grunt-dev-assets#3942

`grunt dev` runs default task
Merge pull request #3949 from novaugust/js-prefixes

`js-` prefix codebase; fix content preview back button
Show settings-cog and back button

closes #3925
- Make user-settings-cog reappear
- Show [< Users] back button