add-server: Make adding server dynamic [WIP].

[akashnimare]

Fixes: #488.

This refactors the code for adding and removing the server so that the app doesn't reload when adding/removing a server.

[priyank-p]

This is getting really close, to be done..., The issue needs to be addressed, is that when adding a server, previous we add them beforehand so we can assume that this.tabs are all sorted and does not have a FunctionalTab now if we add it dynamically there will be if not more than one functional tab for adding an org so we need to filter them out and update the list accordingly which I need to think what we can do.

[zulipbot]

Heads up @akashnimare, we just merged some commits that conflict with the changes your made in this pull request! You can review this repository's recent commits to see where the conflicts occur. Please rebase your feature branch against the upstream/master branch and resolve your pull request's merge conflicts accordingly.

[akashnimare]

@priyankp10 let's spend some time to finish this.