[-] WS: do not escape shop name overzealously

The shop name is likely to contain accented characters and, as it is, it is encoded into a latin-1 representation of UTF-8 input and breaks some XML parsers, like Firefox's:
![PrestaDév](https://f.cloud.github.com/assets/315139/773504/1fc2c518-e93b-11e2-8e63-d4d978605d3d.png)
Only quotes need to be escaped in XML parameters, so we might as well not worry with the rest.