Fire NProgress on User, Post, and Settings save

Closes #3037
- Created `NProgressSaveMixin`, which extends the `save` method of a model
  to fire NProgress.
- Extended `UserModel`, `PostModel`, and `SettingModel` with the new
  mixin.
- NProgress can be disabled by passing an options hash to the save function with the `{disableNProgress:true}`
- Now that the ValidationEngine isn't the only thing playing with options inside of `model#save`, refactored it to pass the options down the super chain.
Some sweets for my sweets
Merge pull request #3263 from joshk/patch-1

Some sweets for my sweets
sugar for my sugar
Merge pull request #3265 from joshk/patch-2

sugar for my sugar
Add status invited-pending for users

no issue
- added status invited-pending for invited users where sending the
invitation email failed
- removed console.log() from authentication.js
Add bower to travis cache
Merge pull request #3212 from novaugust/nprogress-save

Fire NProgress on User, Post, and Settings save
Merge pull request #3260 from sebgie/invited-pending

Add status invited-pending for users
Update Ghost-UI version to ~0.8.0

No issue

- Changes Ghost-UI version to look for any version from 0.8.0 onwards.
Merge pull request #3267 from ErisDS/cache-bower

Add bower to travis cache
Merge pull request #3268 from PaulAdamDavis/bower-ghost-ui-080

Update Ghost-UI version to ~0.8.0
Upgrading bookshelf to 0.7.6 & knex to 0.6.21
Settings: Admin User Tab

closes #2422

- updated to use new change password method
- have all save settings use notifications
- create assetUrl helper for creating asset paths with subdir's properly
 prefixed
- move all url based helpers onto a url object in ghost-paths
Refactoring fixtures

refs #2600, refs #2379

Refactoring fixtures to make permission management a little easier
- Separate fixtures into JSON file and split permissions fixtures from other fixtures
- make fixture migrations more robust by fetching objects, not relying on
  ids and checking before adding
- changed owner fixture slightly to remove any confusion between the 'Owner' role and 'Ghost Owner' user.
- moved 003 fixture versions out of config into logic, possibly not a good
  idea
- refactored permissions fixtures and added permissions_roles fixtures to
  make it easier to read / add
Merge pull request #3253 from hswolff/settings-user-tab

Settings: Admin User Tab
Merge pull request #3238 from ErisDS/issue-2600

Refactor fixtures & fixture migrations to 003
Fix validations on user settings page

Closes #3271
- Change validations on both server and client to allow the
  Website field to be empty or a valid URL.
- Add new schema validation helper isEmptyOrURL.
- Remove duplicate call to UserValidator in the save action
  of the SettingsUser controller.
- User.last_login and User.created_at are already Moment objects
  so Moment#fromNow can be called on them directly.
Migration improvements

refs #2600

- fixed issue with defaults not being populated on upgrade
- added logging to all actions in the migration process to help debugging
  in future
- did a little bit of refactoring
Merge pull request #3272 from jaswilli/issue-3271

Fix validations on user settings page