preserve preceding whitespaces

[reesew]

This is essentially the same as #778, but for Kibana 4. I tested adding the white-space: pre-wrap; css to the table cells, and found that it increases the spacing above and below the line, and I'm not sure how to get rid of the newlines

Before:

After:

The red line indicates the area where preceding spaces show up as desired. The yellow shows the unintended side-effect of my attempt to fix it.