Update gitignore settings with IDE and Mac file settings
First version, search and image details using event bus

Features:
- search for images
- show image details (only title and image) ; go back to search results
- handle errors and no results

This version uses the event bus scoped to Activity (and persisted through configuration changes)
heavily to handle view changes (message / result grid / image detail) "manually" (view are all part
of the same fragment and are "switched" by changing their visibility).
This is stable across rotation happening at any time.