As a developer, I want to manage nodejs-related dependencies and tasks through a single role so that I can simplify existing deploy playbooks.

[thatbudakguy]

Is your feature request related to a problem? Please describe.
Compare #63; this situation is similar: functionality related to javascript/nodejs is spread across multiple roles.

• build_npm
• build_semantic
• run_webpack

Describe the solution you'd like
Implementation could be fairly similar to the django and python roles, with tasks to:

• install an arbitrary version of nodejs
• if present, install nodejs dependencies from a package.json or package-lock.json file
• run arbitrary npm scripts, such as those that compile static files

Additional context
This issue could resolve existing issue #9 related to ansible's npm module; perhaps we now have a newer version or can find a smarter way to use the module.