Check for exp.json before package.json.
Check for exp.json before package.json.

Summary:
- Read project details from exp.json if available (fall back to package.json).
- Fix some console warnings.

Test Plan:
Manual testing with floatyplane (package.json) and new template
project (exp.json).

Reviewers: karen

Subscribers: ben

Differential Revision: D2969

fbshipit-source-id: bc56216

exponentjs/xdl,exponentjs/xdl,exponentjs/xdl