Rename getSlug to slug

another 2 % of #2124
- renamed `/ghost/api/v0.1/posts/getSlug/ to
`/ghost/api/v0.1/posts/slug/`
- renamed method getSlug to generateSlug
Tag archive body_class

closes #2473
- Show tag-template class on tag pages
- Show tag-{{name}} class on tag pages
- Show archive-template only on second page of tag pages
Adding event preventDefault on toggleFeatured function
Merge pull request #2474 from halfdan/2473-tag-body_class

Tag archive body_class
Merge pull request #2477 from AgtLucas/toggle-featured-post-prevent-default

Adding event preventDefault on toggleFeatured function
logError & logWarn call console.log once

fixes #2468
Merge pull request #2469 from ErisDS/error-cleanup

logError & logWarn call console.log once
clears notifications on clicking featured icon

closes #2479

- adds a cleareverything command to toggleFeatured in blog.js to stop stacking of notifications on multiple clicks of featured icon
Merge pull request #2483 from cobbspur/notification

clears notifications on clicking featured icon
Customise slug base name for different models

fixes #2480

- when the santisation of a slug results in an empty string, we use a basename instead.
- this was 'post' and is now the table name for the model, minus the trailing 's'
- this isn't massively robust but works as a temporary fix
Replace spaces in uploaded filenames with hyphens

closes #2485
- use hyphens instead of underscores when santising filenames
- updated tests
Merge pull request #2486 from jaswilli/issue-2485

Replace spaces in uploaded filenames with hyphens
Merge pull request #2484 from ErisDS/issue-2480

Customise slug base name for different models
Redirect feed -> rss

closes #2261

- reserved 'feed' in the list of reserved keywords for slugs
- added a 301 redirect from /feed/ to /rss/
- added a route test, and realised that standard express redirects don't get the right headers
- fixed the headers across all 301 redirects & added tests for the admin redirects
- removed the redirect from /ghost/login/ to /ghost/signin/ as this happens automatically if you're logged out, and isn't very useful if you're logged in as it just redirects again to /ghost/
Unlink import file when finished

fixes #2493
- Update db import version (in case it doesn't exist)
- Properly unlink file after import or error
Prevent adding duplicate tags with different casing

fixes #2478
- Check for existing tags with different case
Escape regex special characters in tag finder

refs #2149
- Properly highlight tags with special characters ($,[,],^,etc.)
Update some server side errors/warnings

issue #2482

- add help messages to all package.json errors/warnings
- change the pageUrl warning to have the correct version numbers
Merge pull request #2488 from ErisDS/issue-2261

Redirect feed -> rss
Fix delete button

closes #2492
- added when.all() to wait until all posts are deleted before deleting
tags
- added a test