Fix to correctly parse single quotes found in a double quote strings

### Issue Summary
Tags with single quotes inside double quotes doesn't get parsed/truncated correctly according to the limit (by words/characters)

### Steps to Reproduce

`ddownsize('<p><img src="/someUrl.jpg" alt="Let\'s get in!"></p><p>hello world</p>', {words:"1"});`
results to:
`'<p><img src="/someUrl.jpg" alt="Let\'s get in!"></p><p>hello world</p></p>'`

But it should result to:
`'<p><img src="/someUrl.jpg" alt="Let's get in!"></p><p>hello</p>'`

This is a bug because the specified number of html words should be followed even if the alt text of the <img> has a single quote/apostrophe.

### Technical details

* Client OS: Windows 8
* Server OS: Windows 8
* Node Version: v0.10.24
* Browser: Chrome

directly related to: https://github.com/TryGhost/Ghost/issues/2106