Change DB backup location

closes #2887
- Stores content files under /content/data/
Fix typo in code comment: propogation errata changed to propagation.
Convert support links from forum to new support site
Merge pull request #2942 from JohnONolan/support-dot-ghost

Convert support links from forum to new support site
Allow schema changes

closes #2354
refs #1641

- added addUnique()
- added dropUnique()
- added addColumn() -> needed for #2330
- dropColumn() is missing due to lack of knex support
- further cleanup of the migrations module
Merge pull request #2939 from jomahoney/db-backup

Change DB backup location
Merge pull request #2941 from jasonsturges/errata

Fix typo in code comment: propogation errata changed to propagation.
Remove redundant function declaration
Fix serializing/deserializing Tags on save from the Editor

closes #2947
- make a PostSerializer to embed the tags objects in the posts POST/PUT request
- on editor save, clear out tags from the post and data store that have `id: null`
Merge pull request #2948 from appleYaks/tags-fix

Fix serializing/deserializing Tags on save from the Editor
Merge pull request #2944 from jaswilli/error-cleanup

Remove redundant function declaration
Merge pull request #2931 from sebgie/issue#2354

Allow schema changes
Fix ALL the things
Concatenate vendor files on change of js in core/shared/
Add all the markerManager stuff to gh-codemirror component
Setup for uploading win
Move marker-manager stuff into a mixin
Fixup markerManager

- make markers a shared object for all that mix it in. makes it easier to use helper functions in different modules
- add getMarkdown method, returns an object with two keys: one with the markdown string with markers, the other without
- make all references to `this.codemirror`, `this.get('codemirror')`
Fixup codemirror component

- make all references to `this.codemirror`, `this.get('codemirror')`
- remove all scroll handlers on willDestroyElement
In EditorView, set markdownViewport scroll class with util, remove extra refs