Update: Use npm for install, update and uninstall where required (fixes #175)

[oliverfoster]

fixes #175 refs https://github.com/adaptlearning/adapt_framework/pull/3370

New

• install, devinstall, update, uninstall, register, unregister and rename using npm for v6

Notes

• install, update, devinstall and uninstall seem to be working well
• Register, unregister and rename are as yet untested