Fizzy Utils, use both Flickity and Infinite Scroll

Hi,

Since updating Infinite Scroll to 4.0 you can no longer use Flickity and Infinite Scroll together as on install you need to choose the right version of Fizzy-UI-Utils.

```
Unable to find a suitable version for fizzy-ui-utils, please choose one by typing one of the numbers below:
1) fizzy-ui-utils#^2.0.0 which resolved to 2.0.7 and is required by flickity#2.2.2
2) fizzy-ui-utils#^3.0.0 which resolved to 3.0.0 and is required by infinite-scroll#4.0.1
```

&

```
Unable to find a suitable version for ev-emitter, please choose one by typing one of the numbers below:
1) ev-emitter#^1.0.2 which resolved to 1.1.1 and is required by flickity#2.2.2
2) ev-emitter#^1.0.1 which resolved to 1.1.1 and is required by unipointer#2.3.0
3) ev-emitter#^2.1.0 which resolved to 2.1.0 and is required by infinite-scroll#4.0.1
```

Reproduce the installation with Flickity 2.2.2 and Infinite Scroll 4.0.1, then inspect the dependency declarations for fizzy-ui-utils and ev-emitter. Done means both packages can be installed together without prompting for incompatible versions.

Written by the indexing model from the issue text.