FreeCodeCamp API: Image Search Abstraction Layer

User stories:

1. I can get the image URLs, alt text and page urls for a set of images relating to a given search string.
2. I can paginate through the responses by adding a ?offset=2 parameter to the URL.
3. I can get a list of the most recently submitted search strings.

Example query usage:

https://image-search-98878.herokuapp.com/api/imagesearch/cats?offset=10
https://image-search-98878.herokuapp.com/api/latest