Remove package-lock from GitHub

The package-lock file has been added to the
gitignore file to prevent future issues for people
who clone our repository.
Ref: https://stackoverflow.com/questions/44206782/do-i-commit-the-package-lock-json-file-created-by-npm-5

Author: Aichnerc

.gitignore

@@ -2,6 +2,7 @@
 
 # Dependencies
 /node_modules
+package-lock.json
 
 # Testing
 /coverage