To allow for spaces in BUILT_BY

diff --git a/Makefile b/Makefile
index 244ae32..1c4f658 100644
--- a/Makefile
+++ b/Makefile
@@ -11,7 +11,7 @@ ifdef DATE
 	GO_LDFLAGS+=-X main.date=${DATE}
 endif
 ifdef BUILT_BY
-	GO_LDFLAGS+=-X main.builtBy=${BUILT_BY}
+	GO_LDFLAGS+=-X 'main.builtBy=${BUILT_BY}'
 endif
 PREFIX?=/usr/local