Add the ability to use and store build cache artifacts

Signed-off-by: Derek Straka <derek@asterius.io>
(cherry picked from commit 0adcc6e0bc)

conf/local.conf.sample

@@ -220,7 +220,7 @@ BB_DISKMON_DIRS = "\
 #file://.* http://someserver.tld/share/sstate/PATH;downloadfilename=PATH \n \
 #file://.* file:///some/local/dir/sstate/PATH"
 
-SSTATE_MIRRORS ?= "file://.* http://build-cache.asterius.io/sstate/PATH;downloadfilename=PATH \n"
+SSTATE_MIRRORS ?= "file://.* http://build-cache.asterius.io/master/sstate-cache/PATH;downloadfilename=PATH \n"
 
 SOURCE_MIRROR_URL ?= "http://build-cache.asterius.io/downloads/"
 INHERIT += "own-mirrors rm_work"