Fix issue #255: use awk to get golang version

Author: hanju-jo

bullet-train.zsh-theme

@@ -536,7 +536,7 @@ prompt_go() {
   setopt extended_glob
   if [[ (-f *.go(#qN) || -d Godeps || -f glide.yaml) ]]; then
     if command -v go > /dev/null 2>&1; then
-      prompt_segment $BULLETTRAIN_GO_BG $BULLETTRAIN_GO_FG $BULLETTRAIN_GO_PREFIX" $(go version | grep --colour=never -oE '[[:digit:]].[[:digit:]]')"
+      prompt_segment $BULLETTRAIN_GO_BG $BULLETTRAIN_GO_FG $BULLETTRAIN_GO_PREFIX" $(go version | awk '{print substr($3, 3)}')"
     fi
   fi
 }