v3.4.1 - Bug fixes

• Event triggered in-app notifications support
  This feature was introduced in v3.4.0(check the release notes for more detail https://github.com/mixpanel/mixpanel-iphone/releases/tag/v3.4.0), this PR is a rewritten of #826 in Objective C to avoid the inconvenience of mixing swift content
  #833

• Bug fix: no need to do additional archive in app crashed tracking
  #832