Git dependency on global install causes install failures with sudo

[justinwb]

In the most recent path release 4.1.4, a user reported being unable to do a global install of solid-server when sudoed as root. Looks like a git dependency has creeped back in. Also we should ensure travis is catching cases like this as part of the resolution.

npm ERR! Command failed: /usr/bin/git clone --depth=1 -q -b gh-pages git://github.com/linkeddata/better-simple-slideshow.git /root/.npm/_cacache/tmp/git-clone-3bcf071d
npm ERR! fatal: could not create leading directories of '/root/.npm/_cacache/tmp/git-clone-3bcf071d': Permission denied

[timbl]

Original gitter char here: https://gitter.im/solid/node-solid-server?at=5baf952c271506518d904424 .. @RubenVerborgh poinst out probably mashlib.
We should then have a test at many levels or at least mashlib that git dependencies havent crept in n

[timbl]

$ cd mashlib/
$ grep git package-lock.json 
      "version": "github:linkeddata/better-simple-slideshow#gh-pages",
      "from": "better-simple-slideshow@github:linkeddata/better-simple-slideshow#gh-pages"
        "better-simple-slideshow": "github:linkeddata/better-simple-slideshow#gh-pages",
$ 

[RubenVerborgh]

Working on this in #797.

In the meantime there is SolidOS/mashlib#18 on Mashlib. Can we use an npm version of better-simple-slideshow, @timbl?

[RubenVerborgh]

Travis now complains if there are GitHub dependencies: https://travis-ci.org/solid/node-solid-server/jobs/435070122

Let's:

• get Mashlib fixed in Remove GitHub dependencies SolidOS/mashlib#18
• update the Mashlib version in Test and fix global package installation #797
• merge Test and fix global package installation #797