fix #448: reader - change the empty view message when fetching articles
s/article/post/ in strings.xml (this word was only used in the reader)
update empty view only when no new article fetched
Merge branch 'develop' into issue/448-reader-empty-page-before-refresh

Conflicts:
	res/values/strings.xml
Merge pull request #457 from wordpress-mobile/issue/448-reader-empty-page-before-refresh

fix #448: reader - change the empty view title when fetching articles