Only use lancache.steamcontent.com for steam (#124)

Resolves #124

steam.txt

@@ -1,51 +1,2 @@
 lancache.steamcontent.com
-*.content.steampowered.com
-content1.steampowered.com
-content2.steampowered.com
-content3.steampowered.com
-content4.steampowered.com
-content5.steampowered.com
-content6.steampowered.com
-content7.steampowered.com
-content8.steampowered.com
-cs.steampowered.com
-steamcontent.com
-client-download.steampowered.com
-*.hsar.steampowered.com.edgesuite.net
-*.akamai.steamstatic.com
-content-origin.steampowered.com
-clientconfig.akamai.steamtransparent.com
-steampipe.akamaized.net
-edgecast.steamstatic.com
-steam.apac.qtlglb.com.mwcloudcdn.com
-*.cs.steampowered.com
-*.cm.steampowered.com
-*.edgecast.steamstatic.com
-*.steamcontent.com
-cdn1-sea1.valve.net
-cdn2-sea1.valve.net
-*.steam-content-dnld-1.apac-1-cdn.cqloud.com
-*.steam-content-dnld-1.eu-c1-cdn.cqloud.com
-steam.apac.qtlglb.com
-edge.steam-dns.top.comcast.net
-edge.steam-dns-2.top.comcast.net
-steam.naeu.qtlglb.com
-steampipe-kr.akamaized.net
-steam.ix.asn.au
-steam.eca.qtlglb.com 
-steam.cdn.on.net
-update5.dota2.wmsj.cn
-update2.dota2.wmsj.cn
-update6.dota2.wmsj.cn
-update3.dota2.wmsj.cn
-update1.dota2.wmsj.cn
-update4.dota2.wmsj.cn
-update5.csgo.wmsj.cn
-update2.csgo.wmsj.cn
-update4.csgo.wmsj.cn
-update3.csgo.wmsj.cn
-update6.csgo.wmsj.cn
-update1.csgo.wmsj.cn
-st.dl.bscstorage.net
-cdn.mileweb.cs.steampowered.com.8686c.com
-steamcdn-a.akamaihd.net
+