Missing ')' at the end of in `install.sh`

Being nitpicky, but if the OS is not recognized, the `install.sh` script returns this message:

```
Either your platform is not easily detectable or is not supported by this
  installer script (yet - PRs welcome!.
```

and maybe it should be:

```
Either your platform is not easily detectable or is not supported by this
  installer script (yet - PRs welcome!). # <- the closing ')'
```

