Typescript type declaration warning.

[tudorelu]

Hey bro, thanks for making this component - I am using it in an app that I'm building.
I encountered this annoying warning when using in typescript environment:

I temporarily fixed it by adding an index.d.ts file containing

declare module 'react-native-simple-stepper';

I'm not sure what the process of updating a package to be 'typescript friendly' is, but I don't think it's a lot more than this for this repo (I might be wrong tho). Might be worth doing... I would be happy contribute it if you don't have the time.

[testshallpass]

I shall add typescript definitions in the future. I definitely think it is helpful.

[testshallpass]

I have added them, see PR #36, thanks.