I'm not sure if there is a built in function or property to do this but as one solution, set the chart frame to -2 for the x origin. Adding your code in the GettingStarted sample app and changing the chart init to the following makes it flush with the edge of the screen (view it's in).
CGFloat margin = UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone ? 20.0 : 50.0;
ShinobiChart *chart = [[ShinobiChart alloc] initWithFrame:CGRectMake(-2, margin, self.view.bounds.size.width, self.view.bounds.size.height - margin)];