Add option to include satusbar in screenshots

All mehotds in BITFeedbackManager that are screenshot releated are changed to include an option that defines wether the screenshot should include the statusbar (if present) or not:

- `- (UIImage *)screenshot` has been changed to `- (UIImage *)screenshotWithStatusBar:(BOOL)includeStatusBar)`
- `- (void)showFeedbackComposeViewWithGeneratedScreenshot` has been changed to `- (void)showFeedbackComposeViewWithGeneratedScreenshotWithStatusBar:(BOOL)includeStatusBar`