handle maps that don't have enUS

[dsjoerg]

https://twitter.com/_celphy/status/393049907101057024

the map is http://EU.depot.battle.net:1119/8b3bce7f9488d824a130cddfff84e84ad460d284a2d9748dd3b08e71605ec66c.s2ma

which has only

enGB.SC2Data\LocalizedData\GameStrings.txt 546 bytes

no enUS.

Due to the issue described here: https://github.com/GraylinKim/sc2reader/blob/master/sc2reader/resources.py#L636

It can't be handled.

Not sure how common this issue is.

[GraylinKim]

This is probably pretty common for non-Blizzard, non-tournament, non-US maps. Why fill in enUS translations when you don't think your map will ever be played over here. I'll see what I can do.