Regenerate package-lock to fix mismatched 'sockjs-client' dependency

Ensures that 'sockjs-client' is locked to an existing version preventing the following error on a clean npm install of the project:

npm ERR! notarget No matching version found for sockjs-client@0.0.0-unreleasable
npm ERR! notarget In most cases you or one of your dependencies are requesting
npm ERR! notarget a package version that doesn't exist.