Upgrade to cordova android@8.1.0 and iOS@5.1.1

• trip end notifications have some minor issues: I will handle this as part of the upcoming upgrade to even newer cordova versions
• OpenID auth code has not been tested: It would be great if somebody who is using OpenIDAuth is able to report on testing results
• Push notifications on iOS require setting IS_GCM_ENABLED to <false> in GoogleServices.plist

This is a beta release since I am immediately planning an upgrade to android@9.0.0 and ios@6.1.0. If that takes too long or is too complex, we can promote this to a full release. But I am hoping it won't come to that.