New RollbarKSCrash module

A new optional module that allows integration of KSCrash reporter into the RollbarNotifier

Hotfix

• fix: resolve #323: Warning payloads are reported as info payloads.

Deprecation warnings removed

• chore: resolve #314: Deprecation warnings break app builds when "treat warnings as errors" is enabled

Numerous incremental improvements

• cleaning up APIs and making them more Swift friendly.
• moving logging level from string value to the RollbarLevel enum type.
• updated conditional compilation preprocessor directives (#elseif into #elif)
• project files updates suggested by the latest Xcode 12 upgrade
• dropping support of iOS v8

Configuration API refactoring and code cleanup

• fully replaced RollbarConfiguration with RollbarConfig
• removed deprecated APIs
• improved Swift APIs
• general code cleanup

v1.12.9 - Default scrub fields and deprecation messages in preparation to upcoming v2 release

• feat: resolve #306: Define default scrub fields
• refactor: resolve #309: Make sure all the public APIs that are to be removed in vNext-2.0.0 are marked for deprecation
• refactor: resolve #307: Change WhitelistFileds into SafeListFields within the RollbarScrubbingOptions