Collapse long descriptions

Submitted by Carlos Soriano Admin Account @csoriano-admin-account

Link to original bug (#730002)

Description

Some 3rd party apps can not follow at all the appStream description guidelines at: http://people.freedesktop.org/~hughsient/appdata/#description cause a very long scroll container which makes the user to not see all the important elements of that page at first glance, like for example: http://i.imgur.com/1dCxGDn.png

Although this should be fixes upstream, in a world of 3rd party apps which we can't control and when we can't manage due to the big amount of them, we should at least make sure gnome-software doesn't look bad at all.

So I think collapse those descriptions, maybe something like android does: http://i.imgur.com/88pK8sP.png

could be nice.