fix react native warnings

[hanwencheng]

close #271 , closes #277

• Remove all the componentWillReceiveProps, componentWillMount, componentWillUpdate method in our code base, whereas the warning with the dependency react-native-markdown-renderer. So I use React Native ignoreWarning method in the entry point of the app, i.e. App.js. in
  e036a5d

• cc53f25 , a68295b Refactored QrView and AccountIcon component with React hooks.

• 0df5839 DataDetail component is not used anywhere, and global styles.js file does not existed, so remove all of them.

• 4fd58b7 : Remove another warning of the iOS Native code threading problem

[Tbaut]

Thanks a lot for that. We are re-factoring quite a lot with YJ right now in #293 and #279 and this will conflict quite a lot I suppose. I'll cherry pick your changes and add them to my branch, I think it'll be a headache otherwise.

[hanwencheng]

I will merge this PR after these bigger ones are merged.

[Tbaut]

Not sure it's a good idea to ignore them. I think it's ok to keep them

[hanwencheng]

It is just annoying, have to click the dismiss button everytime, plus now we have cleaned our code and know that warnings only comes from the dependencies. Let's keep eyes on new code of componentWill* method, I think there is little probabilities that we will use these lifecycles methods since we now have React Hooks to use.

[Tbaut]

I've used hooks now in the substrate re-factoring for this file here: https://github.com/paritytech/parity-signer/pull/293/files#diff-4f18afcbf235db6a111ab00e2a6bee19L24

[hanwencheng]

Nice!

[Tbaut]

All the major PRs have been now so that this one can go in :)

[Tbaut]

Needs review before merging 😞