Update README to include SPM support

Add carthage.sh script to fix building framework with carthage on Xcode 12

Update version in podspec

Implement support for SPM

Fix class to AnyObject warning

Fix issue where progress animation would stop when app is sent to background

Fix issue with jumpy progress animation

Fix issue where dispatch group leave was not called if the app was sent to the background

Update build settings and set deployment target to iOS 10

Merge pull request #9 from Vortec4800/width

Fixed button title width bug

Update README.md

Fix warning for deprecated delegate method

Update podspec for Swift 5

Update project to Swift 5