Installation of plugin from tar.gz file fails
(filing as a new issue in case responses to closed issues aren't monitored)

When trying to install a plugin directly from a tar.gz file per instructions [posted here](https://github.com/oznu/docker-homebridge/issues/254#issuecomment-562915302), installation fails with numerous errors: 

```
npm WARN tar ENOENT: no such file or directory, open '/homebridge/node_modules/.staging/rxjs-00ce25b2/_esm5/internal/operators/index.js'
npm WARN tar ENOENT: no such file or directory, open '/homebridge/node_modules/.staging/rxjs-00ce25b2/internal/operators/index.js'
npm WARN tar ENOENT: no such file or directory, open '/homebridge/node_modules/.staging/rxjs-00ce25b2/operators/index.js'
npm WARN tar ENOENT: no such file or directory, open '/homebridge/node_modules/.staging/rxjs-00ce25b2/_esm2015/internal/InnerSubscriber.js'
npm WARN tar ENOENT: no such file or directory, open '/homebridge/node_modules/.staging/rxjs-00ce25b2/_esm5/internal/InnerSubscriber.js'
npm WARN tar ENOENT: no such file or directory, open '/homebridge/node_modules/.staging/rxjs-00ce25b2/internal/InnerSubscriber.js'
npm WARN tar ENOENT: no such file or directory, open '/homebridge/node_modules/.staging/rxjs-00ce25b2/_esm2015/internal/observable/interval.js'
npm WARN tar ENOENT: no such file or directory, open '/homebridge/node_modules/.staging/rxjs-00ce25b2/_esm5/internal/observable/interval.js'
npm WARN tar ENOENT: no such file or directory, open '/homebridge/node_modules/.staging/rxjs-00ce25b2/add/observable/interval.js'
npm WARN tar ENOENT: no such file or directory, open '/homebridge/node_modules/.staging/rxjs-00ce25b2/internal/observable/interval.js'
npm WARN tar ENOENT: no such file or directory, open '/homebridge/node_modules/.staging/rxjs-00ce25b2/observable/interval.js'
npm WARN tar ENOENT: no such file or directory, open '/homebridge/node_modules/.staging/rxjs-00ce25b2/observable/IntervalObservable.js'
npm WARN tar ENOENT: no such file or directory, open '/homebridge/node_modules/.staging/rxjs-00ce25b2/_esm2015/internal/util/isArray.js'
npm WARN tar ENOENT: no such file or directory, open '/homebridge/node_modules/.staging/rxjs-00ce25b2/_esm5/internal/util/isArray.js'
```

Installation of the plugin after uncompressing the tar.gz file succeeds, but gets overwritten when Homebridge restarts.