Fix podspec tagged version (SnapKit#748)

Co-authored-by: Robert Payne <[email protected]>

Update Podspec

Update min target versions

Update version in Podspec

Update podspec

Update Swift Version

Release v3.2.0 (SnapKit#403)

* make 'layoutConstraints' public again (SnapKit#382)

* Fix wrong function call within contentCompressionResistanceHorizontalPriority (SnapKit#387)

* Missing property topMargin on ConstraintMakerExtendable (SnapKit#393)

This pull request adds the missing property "topMargin" to ConstraintMakerExtendable class.

* Switched main target build settings' "skip install" default settings to YES. (SnapKit#391)

* Add an isActive API to Constraint

* Priority enum (SnapKit#345)

* Adds ConstraintPriority enum to ConstraintMakerPrioritizable

* Constraints priority is now more robust

* Adds priority enum function

* Fixes compile error

* Adds failable initializer. Custom macOS medium priority. Adds back deleted methods

* Updates depracation messages

* Improve Priority API's

* Add extra protocol conformances to ConstraintPriority

* Tweak priority API's for offseting

* Tweak priority API's some more and add tests

* Prepare for release

Prepare release

Fix up iOS 9 / OSX 10.11 availability on Layout Guides

Merge branch 'master' of github.com:SnapKit/SnapKit into develop

# Conflicts:
#	Source/ConstraintMakerRelatable.swift