- When installing a package on Node v8 (or whatever npm version ships with it - v5), all packages not listed in `package.json` are removed. Since we explicitly added `--no-save`, installing a theme would delete the previous one. I am now checking that the file already exists or not. This means that it will still happen to people the next time they run `thelounge install`, because the previous install did not save into `package.json` :/
- Adding `--save` to make sure that the same, correct behavior is done on Node v6 as well (npm v3)
- Adding `--save-exact` for good measure.
- Hides progress bars that flash when installing/uninstalling as it does not bring real value here, at least for now
- Inform user if package being uninstalled was not actually installed
- Do not display npm outputs, mention which version was installed (this will probably need refining when installing packages with dependencies)
