Fix ezjscore CSS packer not recognizing paths to files containing GET parameters with values

Consider the following CSS from [Font Awesome 3.2.1](https://github.com/FortAwesome/Font-Awesome/blob/master/css/font-awesome.css#L28):

```css
@font-face {
  font-family: 'FontAwesome';
  src: url('../font/fontawesome-webfont.eot?v=3.2.1');
  src: url('../font/fontawesome-webfont.eot?#iefix&v=3.2.1') format('embedded-opentype'), url('../font/fontawesome-webfont.woff?v=3.2.1') format('woff'), url('../font/fontawesome-webfont.ttf?v=3.2.1') format('truetype'), url('../font/fontawesome-webfont.svg#fontawesomeregular?v=3.2.1') format('svg');
  font-weight: normal;
  font-style: normal;
}
```

When packing the CSS with `ezjscore_load`/`ezjscore_require` template operators, none of these 5 paths to fonts will not be converted to their absolute paths because the regex is missing the equal sign (`=`), thus not recognizing GET parameters with values (`v=3.2.1`).

This is not intensively tested, but we didn't have any problems on two of our sites using Font Awesome with eZ JS Core CSS packer.