Adds phone field

Similar to text field, uses phone pad keyboard
add Class registration to override type-based Field class selection when field type is default
Add FXFormOptionSegmentsCell, for short option lists.

Also added an example. The SegmentedControl will try to use the entire
cell width if the `FXFormFieldTitle` value is an empty string.
add optionDescriptionAtIndex
Merge pull request #35 from boxer/phone-field

Adds phone field
Merge pull request #39 from sdesimone/master

add Class registration to override type-based Field class selection when field type is default
Updated to 1.2 beta
Merge branch 'master' of https://github.com/nicklockwood/FXForms
Added ability to register cell and controller classes based on field class
Merge pull request #55 from bartvandendriessche/feature/FXFormOptionSegmentsCell

Add FXFormOptionSegmentsCell, for short option lists.
Added FXFormOptionSegmentsCell
Added dynamic fields example
fix FXFormImagePickerCell image width miscalculation
Merge pull request #108 from heychenbin/master

fix FXFormImagePickerCell image width miscalculation
Code cleanup
Improved type inference for dynamic fields
Fixed handling of NSURL fields
Added support for templates collection fields
Fixed issue with accessory views not showing
Fixed issue with button fields turning into text fields
Various option picker methods now also support indexed types
Added some unit tests (more to follow)