Test global package installation on Travis.

Author: RubenVerborgh

.travis.yml

@@ -18,8 +18,12 @@ install:
   - npm ci
 
 script:
+  # Test the code
   - npm run standard
   - npm run nyc
+  # Test global install of the package
+  - npm pack .
+  - npm install -g solid-server-*.tgz
 
 after_success:
   - snyk monitor