changed the default background bubbleView to be clear instead of white
modified the Copy menu to only show for supported contents (UILabel, Image,
ImageView)
added an appendMethod to add new chat data without reloading the entire table
Added indexPath to ChatData so we can call UITableView:reloadRowsAtIndexPaths
Changed groupInterval to a >= comparison so that an interval of 0 will not
group, ever.
Fix to calculation of indexPath
added removeData for an indexPath
Merge pull request #18 from eliburke/master

Improved ability to append and update existing chat, fix to groupInterval, fix to Copy