Change the method sizeWithFont:constrainedToSize:lineBreakMode: is now used to get the subtitle size
Add demo for TDNotificationModeActivityIndicator
Improve documentation
Add new helper method to display a notification with no delay showNotificationInView:title:subtitle:type:mode:dismissible:
Fix typo of word dismissible
Change TDNotificationModeActivityIndicator and TDNotificationModeProgressBar will be forced to use TDNotificationTypeMessage type

This is to avoid conflict with the icons that are used on the other two notification types.