loading indicator for search

This MR is about showing a loading indicator as long as the search API returns a result.

How to test:

1) Prerequisites

• git checkout issue/#95-loading-indicator-for-search
• npm run dev (if it doesn't already)
• point your browser to http://localhost:8080 (or whichever port your runtime env suggests)

2) Test it by:

• click on the search btn located at the top bar

• enter a search term: سرحادوم

expected: => a loading indicator is shown unless the promise returned from axios is fulfilled. once it is, the indicator disappears and the search result is shown instead.

• click on a "page"-button at bottom of the page (pagination)

expected: => same as above

Closes #95 (closed)