s/npm install remark/npm install remark-cli

[mcarton]

Travis build currently fails with the following message:

$ remark -f README.md > /dev/null

Whoops, `remark` is mistakenly installed instead of `remark-cli`

    npm uninstall remark

    npm install remark-cli

See https://git.io/vonyG for more information.

[mcarton]

The Travis failure is still in regex_macros: rust-lang/regex#248.