Integrate the AdMobMediationAdapterFlurry into a swift podspec

[PascalSalesch]

I'm creating a library that will depend on the AdMobMediationAdapterFlurry.

I did the following

pod lib create xxxxxxxxxx

Everything as default (language: SWIFT)

Then I added the following line to my podspec:

s.dependency 'AdMobMediationAdapterFlurry'

Then I run the following command

pod lib lint

 -> xxxxxxxxxx (0.1.0)
    - ERROR | [iOS] unknown: Encountered an unknown error (The 'Pods-App' target has transitive dependencies that include static binaries: (/private/var/folders/8_/1pw469513kv9s8dz8rv1z84m0000gn/T/CocoaPods-Lint-20171213-1923-sl5tv4-xxxxxxxxxx/Pods/AdMobMediationAdapterFlurry/FlurryAdapter/libFlurryAdapter.a)) during validation.

[!] xxxxxxxxxx did not pass validation, due to 1 error.
You can use the `--no-clean` option to inspect any issue.

This currently seems to be a bigger issue for several podspecs using swift.
However it could be resolved by adding the flurry adapter as a vendored framework.

For example, Google offers the following way:

s.vendored_frameworks = 'xxxxxxxxxx/Pods/Google-Mobile-Ads-SDK/Frameworks/frameworks/GoogleMobileAds.framework'

https://developers.google.com/admob/ios/download