Consider moving @MoshiAdapterFactory into it's own artifact

[vanniktech]

It'd be awesome if @MoshiAdapterFactory would be in it's own artifact so that one does not have to use the following:

provided 'com.ryanharter.auto.value:auto-value-moshi:0.4.1'

to add the annotation to the classpath. The big disadvantage is that all of the other classes are also added to the class path (AutoValue components, possible Guava etc).

[serj-lotutovici]

Butterknife does something similar. There's an annotation artefact, that is shared between the runtime library and the annotation processor.