Added code-coverage analysis, via nyc

Author: JamesMessinger

.gitignore

@@ -36,5 +36,5 @@ pids
 node_modules
 
 # Test output
-lib-cov
+/.nyc_output
 /coverage

.travis.yml

@@ -12,4 +12,5 @@ matrix:
     - node_js: 10
 
 script:
-  - npm test
+  - npm run lint
+  - npm run coverage