Added option to remove space after '*' prior const declaration.

This has been a pretty valuable tool for us; now not having to depend on manual addition of constants.
However the generated code didn't match our coding standards and with [Objective-Clean](http://objclean.com/index.php) build phase in place we had to manually fix the code after generating it.

I forked the gem and added an option that removes this space if the option is present; if not it will generate the code like you have it (keeping default behavior to avoid issues with people already using the gem).

New option is `-r` and will produce constants like this:
```objc
extern NSString *const HSGuidedFlow; // On the .h
```
```objc
NSString *const HSGuidedFlow = @"HSGuidedFlow"; // On the .m
```

Everything else is kept the same; the only change is now the ability to specify wether or not to have a space after the `*`.
Don't know if this is valuable for anyone else but I figure if I was going to fork and add it I might as well make it available for you to judge if its worth merging.