Update react-router to v4

[gondzo]

Target version is react-router v4.2.0
Related issue #1196

[gondzo]

This is now complete and merged to test02 branch. Are we OK for merging to dev? @vikasrohit @mtwomey

[vikasrohit]

If routing is working fine there, I guess we can merge.

@mtwomey I am okay with it as we don't have any major release coming up which can conflict with this change.

Update: @gondzo do we have a list which we should checklist for porting to v4 of react router? I mean what all(specifically methods) in the code should be updated along with? One of such cases I think is usage of router.push method which I think is not available in v4 (https://stackoverflow.com/a/42121109/365172).

[gondzo]

Yes, router push is the major difference. Instead of router.push, we are using history.push . Also we are using react-router-dom instead of react-router module.