Added podspec. Cocoapods.

[NikKovIos]

I really need cocoapods back for this!

I ask to remove unused Stevia namespace from cocoapods: CocoaPods/trunk.cocoapods.org#321
Me and people ask to bring back cocoapods: #137

Some reasons to add it back:

• @NikKovIos For Yummypets/YPImagePicker I can't make a new release because Stevia in SPM doesn't support old version of functions and cocoapods not support new names of functions. But YPImagePicker support the both - SPM and cocoapods.
• SPM is a big problem if you haven't internet connection or it is slow.
• @useobjc "I would like to build the pod library as a static library, so that I can get a smaller IPA file size."
• @sdykae "I cant elaborate but my company works with many ipads 4th gen with just ios 10 support, there is no way to get spm on their stack xcode10"

[s4cha]

Hey @NikKovIos sorry for taking so long.
While bringing back Cocoapods doesn't enchant me, I do recognise there is a benefit for the community looking to support old iOS versions/ devices.
I'll try my best to work something out this week :)

[s4cha]

Updated release 5.1.2 to the Cocoapods repo this morning.
The following Podfile works on my end:

source 'https://cdn.cocoapods.org/'
platform :ios, '9.0'

target 'TestSteviaPod' do
  pod 'SteviaLayout', '~> 5.1.2'
  use_frameworks!
end

Note that that the minimum iOS 9 version is iOS9.

@NikKovIos @sdykae @useobjc @vlasov, @shpuntov, @norbdev, @aclassen, @andriipanasiuk, @muhlba91

Let me know if that works for you :)