Patch to sublime_alignment to place spaces at front of line instead of in the middle

This change satisfies my need that I requested at https://github.com/wbond/sublime_alignment/issues/37

Namely, it adds a config option to place the extra spaces of a re-aligned line at the front of the line instead of in the middle.

So, in Objective-C code like this:

  [[NSNotificationCenter defaultCenter]
   addObserver:self
   selector:@selector(onNotification:)
   name:NSWindowDidResignKeyNotification
   object:nil];

... my patch allows this text to be aligned like this:

 [[NSNotificationCenter defaultCenter]
     addObserver:self
        selector:@selector(onNotification:)
            name:NSWindowDidResignKeyNotification
          object:nil];

Thanks!