Switch nvm role for Ansible 2.9 compatibility

[becw]

leanbit.nvm uses syntax that isn't compatible with Ansible 2.9, and hasn't been updated in 3 years so it's unlikely to be fixed.

I've replaced it with elnebuloso.nvm, which is a drop-in replacement (it uses the same variable names). This means that the Vagrantfile doesn't need to be changed for this fix. However, this role hasn't been updated in 2 years and contains syntax that will be deprecated in Ansible 2.11, so we're likely to face a similar issue in 6-12 months.

[lukewertz]

This built great for Tower!

We're oviously still getting the deprecation warning:
TASK [elnebuloso.nvm : install dependencies] *********************************** [DEPRECATION WARNING]: Invoking "apt" only once while using a loop via squash_actions is deprecated. Instead of using a loop to supply multiple items and specifying pkg: "{{ item }}", please use pkg: ['git', 'curl', 'sudo'] and remove the loop. This feature will be removed in version 2.11. Deprecation warnings can be disabled by setting deprecation_warnings=False in ansible.cfg.

But that's known and anticipated.

Based on my one successful build, I say this is good to go! :)