Swipe for paging, fixed frame for caption

Added support for paging through the CoachMarks using swipe gestures,
with an indicator. Added optional fixed frame for caption label.
Continue text matches caption style, minor memory fixes.
Isn't
```Objective-c
@synthesize enablePaging = _enablePaging;
```
the same as 
```Objective-c
@synthesize enablePaging;
```