Add native display mode and show from user-defined navigationController

[ferrisxie]

In order to display JBWebViewController in a more native view , I added some method and change some code of the origin issue.

• Added:

typedef enum : NSUInteger {
    JBWebViewTitleModeDefault=0,
    JBWebViewTitleModeNative,
} JBWebViewTitleMode;

• Added:

- (void)showFromNavigationController:(UINavigationController*)navigationController;

View the .m file to see more details.
Best Wishes.