PromisesSwift cannot be integrated as a static library

When creating an app that depends on pod 'PromisesSwift' and that uses static libraries,I get the following error:

```
[!] The following Swift pods cannot yet be integrated as static libraries:

The Swift pod `PromisesSwift` depends upon `PromisesObjC`, which does not define modules. To opt into those targets generating module maps (which is necessary to import them from Swift when building as static libraries), you may set `use_modular_headers!` globally in your Podfile, or specify `:modular_headers => true` for particular dependencies.
```

An example podfile for this would be the following:

```
source 'https://github.com/CocoaPods/Specs.git'

target 'CocoaPodsDebug' do

# Comment the next line if you don't want to use dynamic frameworks

#use_frameworks!

pod 'PromisesObjC'
pod 'PromisesSwift'

end
```

note that `use_frameworks!` is commented out, also if we add `:modular_headers => true` to pod 'PromisesObjC'` the error goes away.

The question is: are there any plans to make this work by default?