Resolvi meu problema adicionando as seguintes linhas no meu arquivo conf vhost:
<Directory /home/nexusstar/workspace/{{path to js folder}}/js>
AddEncoding gzip gz
ForceType text/javascript
</Directory>
<Directory /home/nexusstar/workspace/{{path to css folder}}/css>
AddEncoding gzip gz
ForceType text/css
</Directory>