NVM Global install Option

[morgangraphics]

Installing NVM in a global space e.g. /opt/nvm requires that:

1. The destination directory and grand/parent directories are not protected or limited by permissions of which the become_user are not a part of
2. The become_user has sudoers access to be able to create directories in the file system and execute commands in that space
3. The become_user is part of a group that has some sudoers access to create directories in the file system and execute commands in that space

While the role will work if these scenarios have been addressed before hand (the user handles it themselves outside this role), it might be beneficial to have a global_install option that will set up the appropriate secure/least privilege permissions to handle permission sensitive install scenarios. e.g. nvm-users

As it stands now, installing in /opt/nvm requires that you have root permissions to create the directory and to run the install.sh file which in turn tries to create a series of other directories under /opt/nvm like /opt/nvm/[.cache|alias]. Consequently, by adding become: true and become_user: root the nvm script execution will attempt to install Node as root, you can't install Node as root and will subsequently fail.