(bug 62613) Notification excerpt lengths are inconsistent

Language::truncate doesn't get rid of html entities, which can lead to text
being truncated in the middle of HTML tags, which is bad (also: that html counts
towards the truncate character count & it shouldn't)

Bug: 62613
Change-Id: I0560cc2d0cdca8d399d658e90b9a0cab2aa8bd10
Merge "(bug 62613) Notification excerpt lengths are inconsistent"