make changes backwards compatible (Refs #431)

config/tendermint/config.go

@@ -13,6 +13,10 @@ func getTMRoot(rootDir string) string {
 	if rootDir == "" {
 		rootDir = os.Getenv("TMHOME")
 	}
+	if rootDir == "" {
+		// deprecated, use TMHOME (TODO: remove in TM 0.11.0)
+		rootDir = os.Getenv("TMROOT")
+	}
 	if rootDir == "" {
 		rootDir = os.Getenv("HOME") + "/.tendermint"
 	}