Closes #443
Merge pull request #444 from dim0v/develop

fixes #443
fix imports for projects without a pch. bump version numbers. fix podspec assets. close #435
fix podspec again. #435
version 5.2.3
fix podspec. close #449
move status bar notification handling to keyboard controller
refactor keyboard delegate/notification methods to single notify helper method
update collection view docs
remove status bar notifications from keyboard controller, re-add to view controller. fix in-call status bar layout issues. close #434
remove duplicate layout constraints in xibs. close #264
version nums
fix import
adjust toolbar constraints
fix demo
fix toolbar constraint issues and button widths not setting properly. fixes #460
move collection view delegate and data source definitions to their own header files to clean up collection view header.
move JSQMessagesCollectionViewCellDelegate implementation from controller to collectionView
reset cell text on prepareForReuse. #316
improve cell selection and menu handling. close #261