style(cli): add some color to error messages

pkg/cmd/grafana-cli/commands/commands.go

@@ -4,6 +4,7 @@ import (
 	"os"
 
 	"github.com/codegangsta/cli"
+	"github.com/fatih/color"
 	"github.com/grafana/grafana/pkg/cmd/grafana-cli/log"
 )
 
@@ -12,7 +13,7 @@ func runCommand(command func(commandLine CommandLine) error) func(context *cli.C
 
 		cmd := &contextCommandLine{context}
 		if err := command(cmd); err != nil {
-			log.Error("\nError: ")
+			log.Errorf("\n%s: ", color.RedString("Error"))
 			log.Errorf("%s\n\n", err)
 
 			cmd.ShowHelp()

pkg/cmd/grafana-cli/commands/install_command.go

@@ -132,7 +132,7 @@ func downloadFile(pluginName, filePath, url string) (err error) {
 			} else {
 				failure := fmt.Sprintf("%v", r)
 				if failure == "runtime error: makeslice: len out of range" {
-					err = fmt.Errorf("Failed to extract zipped HTTP response. Please try again.\n")
+					err = fmt.Errorf("Corrupt http response from source. Please try again.\n")
 				} else {
 					panic(r)
 				}