you can now filter by project name. Also sensible defaults

libgrabber will work parameterlessly if you are in the jsdelivr directory. Also you can use --projects-filter=Regex to filter by project name. This is useful if you want to just test a project you are adding
Should the filtered and non filtered versions be separated into two separate functions?

For instance `updateAll` could be modified to

```
return updateFiltered(jsDelivrPath, projectsPath, {test: _.constant(true)});
```