New fields and some fixes.

Hello.
I have some additions to IBAForms library.
Basically, it is form field which depends on several key paths, one field made ​​based on it (this is read-only text field with block which invoked on tap) and field with multiple lines. Also I added possibility to inserting and deleting sections to table view with animation. In IBAFormsShowcase project I added examples of new form fields.