Made bash completion command optional; still need to update documentation

flag.go

@@ -7,6 +7,9 @@ import (
 	"strings"
 )
 
+// This flag enables bash-completion for all commands and subcommands
+var BashCompletionFlag = BoolFlag{"generate-bash-completion", ""}
+
 // Flag is a common interface related to parsing flags in cli.
 // For more advanced flag parsing techniques, it is recomended that
 // this interface be implemented.