feat: ionSpinner customization in refresher and infinite scroll

[danjohnso]

Type: feat

Platform: all

It would be nice to be able to add the color class to the spinner from the refresher and infinite scroll directives. Looks like right now we can only change what the icon type is. Natural follow up to #3077

[felquis]

+1 👍

I think something like this would be nice!

<ion-infinite-scroll
  on-infinite="loadMore()"
  distance="10%"
  spinner-class="spinner-light or-something-else">
</ion-infinite-scroll>

I also noticed that when using infinite-scroll with ng-repeat, the spinner appears where I put the ion-infinite-scroll directive, so may be useful to use the content of this directive to show a completely different loading, to let developers use whatever they want to, like:

<ion-infinite-scroll
  on-infinite="loadMore()"
  distance="10%"
  use-content="true">

  <p>
    <ion-spinner class="spinner-light"></ion-spinner>
  </p>

  Loading
</ion-infinite-scroll>

[felquis]

I bit related to #3343

[mhartington]

Closing this as a feature request and moving to our trello board
https://trello.com/c/pedEiFm5/93-allow-classes-for-ion-refresher-and-ion-infinite-scroll