fix(cli): Remove default files from CLI

The default files should be in one place (`ava-files.js`).
Right now the defaults provided in `ava-files.js` aren't being used
because the CLI pre-populates them.

Closes avajs#875

Author: Kent C. Dodds

cli.js

@@ -165,13 +165,6 @@ api.on('test-run', function (runStatus) {
 });
 
 var files = cli.input.length ? cli.input : arrify(conf.files);
-if (files.length === 0) {
-	files = [
-		'test.js',
-		'test-*.js',
-		'test'
-	];
-}
 
 if (cli.flags.watch) {
 	try {