_s: Simplify entry meta output

- Fix entry-footer inconsistency between content-*.php files
- Move in a function <code>_s_entry_meta()</code> to avoid duplication

---

At the moment there is an inconsistency between content.php and
content-single.php regarding the .entry-footer output.

In my opinion content.php output is would be better to use because it's
easier to translate and allow more customisation.

Finally by moving it into <code>inc/template-tags.php</code> we are
getting rid of some duplicated code.
Remove Domain Path from style.css

Indicating a domain path is optional, if you use the default, there is
no need to specify it.
Setup is a noun. Set up is a verb. "Setup the WordPress core custom header feature." is incorrect. "Set up the WordPress core custom header feature." is correct.
Merge pull request #554 from Automattic/fix-setup-typo

Setup is a noun. Set up is a verb.
Add escaping to custom header example. Make sure that proper attribute escaping is added into the example that's in the custom header include file. Since we're not including this in header.php, we should at least make sure that the example given is proper and passes WordPress Coding Standards checks. See #552 for context.
Initial commit for _sass.

Props @michaelArestad @hugobeta, and @jacklenox.

* Give prefix to variable files. This avoids confusion with files of similar names like typography. It also helps with the visual recognition over what file does what.
* Set up mixins-master.
* Setting foundation for encouraging in larger projects use of more than one mixing file. This creates a master mixins file that we can then bring subs into if the project grows.
* Fixed line breaks, spacing and new lines. Props @gregrickaby.
* Nest widget select. Props @gregrickaby.
* Make variables be variables-site. Makes this the global variables folder. People can then use sub folders in sections for local only variables.
* Change content directory to be site directory.
* Remove zip. Revert `style.css` to not be auto generated version.
* Fixes rem size issue on body font.
* Fixes for differences between `_s` and `_sass`. Fixed font sizes, added in display block to classes so they compile and the theme check
passes.
* Remove text domain and clean up css.
_s: Bring back closing curly brace.

Erroneously removed while trying to sort out a merge conflict, when I
squashed `_sass` commits.
Merge pull request #550 from Automattic/_sass

Brings sass into _s

Sass now comes with _s - you can simply check an option on underscores.me and get a version with Sass.

Props to: @gregrickaby @bradp @hugobaeta @obenland @sabreuse @MichaelArestad @jacklenox @karmatosed
Adds in missing class

Brings in class that was missing from updated Sass but in style.css.
Props @corvannoorloos
Put vendor specific property first
Update _mixins-master.scss
Merge pull request #568 from fsylum/master

Reordering vendor-prefixes property in the mixin: props @fsylum
Puts width in right place

Props @corvannoorloos
indentation using tabs instead of mixed tabs/spaces

see https://github.com/Automattic/_s/pull/565
Update input field border color

now matches style.css
Merge pull request #570 from corvannoorloos/patch-1

Indentation using tabs instead of mixed tabs/spaces- props @corvannoorloos
Merge pull request #571 from corvannoorloos/patch-2

Update input field border color props @corvannoorloos
Prepare Underscores for Coding Standards. See https://github.com/Automattic/_s/issues/553.
Prepare Underscores for Coding Standards. See https://github.com/Automattic/_s/issues/553. [skip ci]
Merge pull request #581 from philiparthurmoore/master

Introduce Coding Standards Checks into Underscores