Fix Redefinition of module error in Xcode ≧ 8.3

[vkedwardli]

Renamed module.modulemap to Starscream.modulemap to avoid Xcode bug, according to Xcode 8.3 release notes:

When building a framework that has module maps in both the source and the install directories that define the same module, the compiler will show a redefinition message. (28638816)
Workaround: Rename the module map file in the source directory to a non-default name (the default name is module.modulemap or module.map), and set the Module Map File build setting to the renamed module map.

Reference:
ResearchKit/ResearchKit#922
grpc/grpc#10355

Should can fix the error mentioned by @rhishikeshj in #361 (comment)

p.s. I'm still facing it in Xcode 9, reproducible with multiple projects in different folder having Starscream as the same dependency

[vkedwardli]

Seems there is no easy way to fix this since the SDK itself is using module.modulemap and will trigger the same Xcode bug if I try to target all macOS/iOS/tvOS/watchOS platforms

May be it is not possible to support both local project + Cocoapods at this moment