remove .jscsrc config and remove gulp-jscs from package.json

All tests pass and build completes.
This is no longer needed since we migrated to eslint. (REF: https://eslint.org/docs/user-guide/migrating-from-jscs)

Author: coliff

.jscsrc

@@ -141,8 +141,7 @@ gulp.task('lint:js', () =>
   gulp.src([
     `${dirs.src}/js/*.js`,
     `${dirs.test}/*.js`
-  ]).pipe(plugins().jscs())
-    .pipe(plugins().eslint())
+  ]).pipe(plugins().eslint())
     .pipe(plugins().eslint.failOnError())
 );