Simplify publish date checks

Fixes #814

- Changed to compare instances of `moment` using it's built in
comparison function instead of string compare with the date from the
database.
- Ensure compared date is parsed with the correct formats that we were
supporting before #1107.
- Moved date formats to variables to reduce chance for error in future.
Allow themes to provide custom error template.

fixes #1212, #1213
Store the Bookshelf instance on the Bookshelf module

- Assigns the ghostBookshelf instance to the Bookshelf.ghost property
adds prefix option to tag helper

        closes #607

 - added prefix attributetor tags helper
 - will add prefix only if tags are present
 - adds unit tests for prefix
Removed special character from SCSS

Replaced it with the escaped unicode version (\21AA).
Issue/1007: Corrected the behaviour of the HOME and END keys on the CodeMirror editor by overriding their calls in the extraKeys config of the editor
Merge pull request #1241 from matthojo/Unicode-fix

Removed special character from SCSS
Merge pull request #1218 from halfdan/1212-themable-error-pages

Allow themes to provide custom error template.
Merge pull request #1239 from cobbspur/tagsprefix

adds prefix option to tag helper
Replace nodejs-bcrypt with bcryptjs

* https://github.com/shaneGirish/bcrypt-nodejs
* https://github.com/dcodeIO/bcrypt.js
Merge pull request #1248 from halfdan/bcryptjs

Replace nodejs-bcrypt with bcryptjs
Add validation for importer

closes #952
- moved api.js to api/index.js
- added api/db.js for import and export functions
- moved /ghost/debug/db/export to GET /api/v0.1/db
- moved /ghost/debug/db/import to POST /api/v0.1/db
- removed /ghost/debug/db/reset
- added validation for import
- added constraints object to migration
Merge pull request #986 from sebgie/issue#952
Fixed style of modal in preview.

fixes #1179
Merge pull request #1202 from halfdan/1179-modal-styles
Replace new-lines with spaces in excerpt helper.

fixes #531
Add core/server.js to grunt watch
Explicitly add Ruby dependencies to project via Bundler

closes #1220
- This uses Bundler to install Ruby dependencies to handle explicit
  dependencies in provisioned environments
- The initial Gemfile contains SASS dependencies (sass and bourbon gems)
State that Bourbon files are generated in CONTRIBUTING guide

Fixes #1255.
- This says that the Bourbon directory is generated and does not
  ambiguiate with the installation of the bourbon gem
Fix duplication of entries in infinite scroll

Fixes #1242

- Switched to render each new item as its added to the collection when
retrieving via scroll checks.
- Added check to remove all subviews whenever `render` is called on
`ContentList` as a preventative measure.
- Cached the jquery reference to the ordered list in `render`.