Pulled out app paths to separate config and added a check for required files in start script

[christophior]

PR is still a work in progress mainly because for some reason installing the module globally on my local machine to test was not working and even installing the module from npm doesn't work so I haven't really been able to test this -_-

I keep getting a prompt saying that the create-react-app command is not found.

Anyways...
I also feel like I should add some logic where the browser doesn't attempt to open if there are any missing required files, maybe don't even compile if any files are missing.

Referencing issue #96

If someone wants to build on top of this PR feel free too as well, just leave a comment below in case I or someone else wants to continue this.

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[vjeux]

Both myself and @lacker have the issue of npm install -g react-native not working. Would be awesome to investigate and figure out why

[christophior]

@vjeux interesting, when I start working on this again i'll look into that issue as well.

[gaearon]

By the way I started making the path change (although in a different way) in #191.

[gaearon]

I’m going to close this because it got out of date.
This was a bit hard to review because it contains two unrelated changes.

We still need help on #96 so please feel free to resubmit focusing on that feature in particular.
Thank you!

[christophior]

Makes sense, the portions of the changes (path changes) seem to already be made so i'll look into the changes and try making another PR that solely focuses on fixing the issue if no one is already pursuing #96.