README updates

Revert "Removed unrecognized swift version from podspec"

This reverts commit 6adb9da.

Bump podspec to 3.1.0 tag

Merge pull request Weebly#27 from mxcl/master

Add SwiftPM support

Add swift version to podspec

Merge pull request Weebly#19 from Weebly/swift-4

Swift 4

Make frameworks shared schemes

Update podspec to 2.0.6

Update Podspec

Update podspec