gitignore: ignore *.log, release directory

Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>

.gitignore

@@ -2,10 +2,12 @@
 /gopath
 /gopath.proto
 /go-bindata
+/release
 /machine*
 /bin
 .vagrant
 *.etcd
+*.log
 /etcd
 *.swp
 /hack/insta-discovery/.env