Update europe.geojson Lithuania boundary

Updated boundaries of Lithuania to reflect this issue I created a while back:

https://github.com/codeforamerica/click_that_hood/issues/238

(N.B. This isn't a controversial political boundary; it's been like this for a really long time and it's not disputed by Lithuania/Russia. Just a fairly large error in the maps.)
Merge pull request #248 from nluchs/patch-2

Update europe.geojson Lithuania boundary