Add detection for the react-scripts executable
Add detection for the react-scripts executable

When a project is bootstrapped with create-react-app using the latest
versions of node/npm, the react-scripts executable is installed in the
top level node_modules/.bin directory. This has been added as the first
path to check.

This fixes #161, closes #39, closes #113 and resolves facebookincubator/create-react-app#2709, and closes #125.

orta/vscode-jest,bookman25/vscode-jest,bookman25/vscode-jest,bookman25/vscode-jest,orta/vscode-jest,orta/vscode-jest