`nvm install`: Add support for `--lts` and `--lts=argon`
`nvm install`: Add support for `--lts` and `--lts=argon`

PeterDaveHelloKitchen/nvm,lukechilds/nvm,lukechilds/nvm,ljharb/nvm,creationix/nvm,evocateur/nvm,creationix/nvm,evocateur/nvm,PeterDaveHelloKitchen/nvm,edwmurph/nvm,ljharb/nvm,PeterDaveHello/nvm,PeterDaveHello/nvm,edwmurph/nvm