Update Flow version to v0.34.0

[koba04]

This PR is to update Flowtype version to v0.34.0 and fix some errors.

In Flowtype v0.34.0, dictionary types are treated as invariant.

• https://github.com/facebook/flow/releases/tag/v0.34.0

In the following case, it has to explicit covariance with +.

• ReactNativeAttributePayload.js

type AttributeConfiguration =
  { [key: string]: (
    CustomAttributeConfiguration | AttributeConfiguration /*| boolean*/
  ) };

But I avoid the error by using $FlowFixMe comment because it's needed some works like this.

1. The covariant syntax(+) causes a parse error in ESLint.
2. To fix it, we have to update babylon for parse covariant syntax with +.
3. 2. causes other ESLint errors, which are no-undef for type parameters.
4. To fix them, We have to use eslint-plugin-flowtype.
5. To install eslint-plugin-flowtype, We have to update ESLint to >=2.0.0 because of peerDependencies.
6. 5. causes other ESLint errors, We have to fix them.

Can I work on this?
If so, I'll work on this as other PRs.

[chicoxyzzy]

IMO it's worth it

[koba04]

resolved by #8259