Security issue in marked 0.3.6

[elwynelwyn]

Node Security project has flagged Marked 0.3.6 as insecure.

https://nodesecurity.io/advisories/531

This in turn makes angular-marked insecure, and causes our build to fail.

Marked is no longer maintained by the looks of things:

markedjs/marked#938 (comment)

Would be great if the underlying library this project uses could be swapped, perhaps to the suggestion here:

#76