News: Find out if we trimmed inside a bold tag.

Close it if we did:
>>> ddg_spice_news.ellipsis("US President Barack <b>Obama said</b> Tuesday.", 40)
"US President Barack <b>Obama said</b> ..."
>>> ddg_spice_news.ellipsis("US President Barack <b>Obama said</b> Tuesday.", 35)
"US President Barack <b>Obama</b> ..."
News: Changed the ellipsis function.

It's simpler to just count the number of open and closing tags. If there is a mismatch (we cut between two tags), then we just append a closing tag.
Merge pull request #240 from duckduckgo/jag/bolding

News: Find out if we trimmed inside a bold tag.