.dylib and static lib fix

[ksiazkowicz]

When trying to use your library, I noticed two things:

• I can't really link against it dynamically on my Mac because linker expects a .dylib, not a module,
• If I link statically against libabieos.a, it's missing symbols from abieos.cpp. I'm not sure if it's OK with you to add it to the main file so I added another build target called abieos_static