atom: use http download instead of git.

Makes update check work with atom and verifies the source package.

srcpkgs/atom/template

@@ -10,12 +10,9 @@ short_desc="Chrome-based text editor from Github"
 maintainer="Andrea Brancaleoni <miwaxe@gmail.com>"
 license="MIT"
 homepage="https://atom.io"
+distfiles="https://github.com/$pkgname/$pkgname/archive/v$version.tar.gz"
+checksum="27dadd5b9a63d53e75ff662123960b1ddca6e6dd84073983306b4717854beee0"
 
-do_fetch() {
-	local url="git://github.com/${pkgname}/${pkgname}"
-	msg_normal "Fetching source from $url ...\n"
-	git clone --branch v${version} ${url} ${pkgname}-${version}
-}
 do_build() {
 	script/build
 }