Added ADDatePicker
Added ADDatePicker

Adding ADDatePicker to UI -> PickerView

## Project URL
https://github.com/abhiperry/ADDatePicker

## Category
UI -> PickerView

## Description
A fully customizable iOS Horizontal PickerView library, written in pure swift
 
## Why it should be included to `awesome-ios` (optional)
 - ADDatePicker is customizable iOS Horizontal PickerView library. There are not much PickerView libraries out there which supports Horizontal layout.

## Checklist
<!--- Go over all the following points, and put an `x` in all the boxes that apply. -->
<!--- If you're unsure about any of these, don't hesitate to ask. We're here to help! -->
- [x] Only one project/change is in this pull request
- [x] Addition in chronological order (bottom of category)
- [x] Supports iOS 9 / tvOS 10 or later
- [x] Supports Swift 4 or later
- [x] Has a commit from less than 2 years ago
- [x] Has a **clear** README in English
vsouza/awesome-ios,arasu01/awesome-ios