RA adding blitzkrieg & burlesca balanced maps

I am so sorry for creating this fresh pull request. Interactive rebasing didnt worked for me, and while trying to use commands in smartgit which i havent fully understand (e.g. cherry pick) I have made a mess in local repo. While I was affraid that there will occure conflicts, I had reforked OpenRA and made clean push. Please dont blame me.

continuation from https://github.com/OpenRA/OpenRA/pull/4739

maps
http://content.open-ra.org/?p=detail&table=maps&id=1562
http://content.open-ra.org/?p=detail&table=maps&id=1560

*As far as I checked all the AI bots, there is no problem with game lag after destroying bridges, there is no other glitches too.