Update config.theme() after every settings edit

fixes #1645

- removes server.get('ghost root') as it is only an alias
to config.paths().path, and adds unnecessary indirection
- removes config.theme().path as its just an alias to
config.paths().path, updated all relevant references
- update config.theme.update to only require the api/settings object,
and no longer need the config object
- modify api/settings.edit to call config.theme.update so that
the themeObject is ready for next rendering of template
Change message when unsupported node version is used

no issue
- changed ‚the latest‘ to ‚a supported‘

Reason: the user is asked to update to the **latest** version of
node.js when v0.11.* is installed but v0.10.* is required
Bug fixes for partial views

closes #1203
- Update express-hbs module to the new version (0.5.2)
- Use two instance of hbs one for the theme and an other for the admin
- Template helpers are register as partial view
- Partial views of the theme are reload when the theme changed

Remove clear partial cache in handlebars

This code will be move in `express-hbs`.
This doesn't cause a problem to remove this line but it is not clean.

Remove unused hbs instance

Resolve conflict
Fixed admin 404 page broken image refrence
Merge pull request #1660 from sebgie/version-number

Change message when unsupported node version is used
Merge pull request #1606 from Gotvitch/issue1203

Bug fixes for partial views
Standardize file path access throughout ghost

resolves #1390

update all string based references to file paths
to use the ./core/server/config/paths file
so that it is the single source of truth
Merge pull request #1651 from hswolff/issue-1645

Update config.theme() after every settings edit
Merge pull request #1662 from PaulAdamDavis/master

Fixed admin 404 page broken image refrence
CSS and layout fixes for image uploader

closes #1673
- dropzone icon doesn't appear when filestorage is false
- proper cursor and no selection on icon
- cleaned up some sass
Merge pull request #1674 from ErisDS/css-fixes

CSS and layout fixes for image uploader
Improve Helpers

closes #1640
closes #1672
- changed to include config using require
- deleted has_tag helper
- deleted json helper
- removed fileStorage and ghostScriptTags helpers from frontend
- added fileStorage and url helper to admin
Add Force SSL Configuration/Middleware

Solves #1300
- Adds forceAdminSSL bool config value
- Adds checkSSL middleware
- Adds redirectSSL helper function
Merge pull request #1542 from pmgarman/ssl
Bug fixes, undefined should not be a string
Merge pull request #1675 from sebgie/issue#1640

Improve Helpers
Merge pull request #1636 from hswolff/standardize-path-access

Standardize file path access throughout ghost
CasperJS waitForOpaque fails more gracefully