Make IQ work when keyboard is already shown

Make IQKeyboard work when the keyboard is already shown and the
UITextField/UITextView becomes first responder (in this case
UIKeyboardWillShowNotification is not fired). Also IQ before this
change didn't work for me for UITextView (worked only for UITextField).
After the change IQ is working well both for UITextField and UITextView.
Merge branch 'master' of https://github.com/hackiftekhar/IQKeyboardManager

Conflicts:
	KeyboardTextFieldDemo/IQKeyBoardManager/IQKeyBoardManager.m
Adding keyboardDistanceFromTextField only once instead of every time the frame is adjusted
Merge pull request #7 from mrvincenzo/master

Adjust frame correctly when switching between field when keyboard is already shown