Add "Expand all" in the Pages report footer

[matt]

In the various reports in the Pages section in Piwik, entries are collapsed by default. If a user wants to get a global view of the report, he would have to click on each row to expand them all individually.

In the reports footer, under the + image, we could add an Expand All link that would, on click, expand all rows in the table. Currently, it is possible to do the same by searching for the " " (space) string in the search box at the bottom of the table. Showing an actual link would improve greatly the user experience.