Attribute replacement doesn't work with minified HTML

[stewartyu]

Some sites use minified HTML, which can strip out quotation marks like this:

<img src=/img/icon/cauldron.8d73.png>

We want capturejs should change this to:

<img x-src=/img/icon/cauldron.8d73.png>

However, the regex requires the value to be wrapped by either " or ' which causes this to be skipped.