Preserve query text newlines in tooltip

Example in SSMS:

![image](https://user-images.githubusercontent.com/4189474/34502605-2040e916-f00c-11e7-9d50-8f4c2eb722cb.png)

This wrapped into a single line in html-query-plan

![image](https://user-images.githubusercontent.com/4189474/34502624-30eaaa36-f00c-11e7-99a9-2c8f1701319a.png)