closes#4850
- fixed `meta_description` and `meta_title` when used within a `{{#foreach}}`
- `meta_description` and `meta_title` now depend upon the current context
to get the right string (author bio, tag description, ...).
Note: `ghost_head.js` and `ghost_head_spec.js` have been touched to add
the required context information when calling the helpers.
No issue
- Tag Meta title and description override default response
- Tag Meta title present on all pages
- Tag Meta description available only on first page
- Updates tests
no issue
- Split theme helpers into individual files for each
- Do the same for tests
- Have utils to share some things between them
- Move assetHash onto config