Adds CSS classes from category configuration to catalog filter and list html client
Removes warning as products that are virtual can have no stock
Minor semantic and layout improvements
Merge pull request #81 from nsendetzky/master

Minor semantic and layout improvements, removes warning in stock manager
Returns empty string instead of null in html clients if an error occurs
Translates search texts
Merge pull request #82 from nsendetzky/master

Fixes returned value on error in html client and translates search texts
Merge https://github.com/Arcavias/arcavias-core