Functions to new module. Tidies up reused code into
private function.
Throws warning due to line 11 in command.rs - unused import
Import is used for the StructOpt derive macro, so is needed
but still throws this warning
npm allows scopes to avoid name collisions. In order to support this
optional feature a flag has been added so that the name in the generated
package.json is correct.
Example for a package named wasm-add:
```bash
wasm-pack init
```
package.json
```json
{
"name": "wasm-add"
}
```
```bash
wasm-pack init --scope mgattozzi
```
package.json
```json
{
"name": "@mgattozzi/wasm-add"
}
```
Andy Bell