Fix no result messages on "New translation" dialog
- Fix "No pages found for $1 in $2", where $1 is query input and
$2 is selected source language. When there are no pages for given
search query, message is displayed. If source language changes, both
$1 and $2 stay the same, but source language ($2) should change.
- Change how no result messages are centered, without using additional
DOM element to wrap centered text.
- Add pending indicator when recent edits are fetched. This should be
apparent when there is input query in "New translation" dialog and
source language is changed.