Add tslint for grid-list demos disabling "no-relative-import-in-test"

This replaces the disabling comments in the `.tsx` files.

Author: Dudrie

docs/src/pages/demos/grid-list/AdvancedGridList.tsx

@@ -6,7 +6,6 @@ import GridListTile from '@material-ui/core/GridListTile';
 import GridListTileBar from '@material-ui/core/GridListTileBar';
 import IconButton from '@material-ui/core/IconButton';
 import StarBorderIcon from '@material-ui/icons/StarBorder';
-// tslint:disable-next-line: no-relative-import-in-test
 import tileData from './tileData';
 
 const styles = (theme: Theme) =>

docs/src/pages/demos/grid-list/ImageGridList.tsx

@@ -3,7 +3,6 @@ import PropTypes from 'prop-types';
 import { withStyles, Theme, createStyles, WithStyles } from '@material-ui/core/styles';
 import GridList from '@material-ui/core/GridList';
 import GridListTile from '@material-ui/core/GridListTile';
-// tslint:disable-next-line: no-relative-import-in-test
 import tileData from './tileData';
 
 const styles = (theme: Theme) =>

docs/src/pages/demos/grid-list/SingleLineGridList.tsx

@@ -6,7 +6,6 @@ import GridListTile from '@material-ui/core/GridListTile';
 import GridListTileBar from '@material-ui/core/GridListTileBar';
 import IconButton from '@material-ui/core/IconButton';
 import StarBorderIcon from '@material-ui/icons/StarBorder';
-// tslint:disable-next-line: no-relative-import-in-test
 import tileData from './tileData';
 
 const styles = (theme: Theme) =>

docs/src/pages/demos/grid-list/TitlebarGridList.tsx

@@ -7,7 +7,6 @@ import GridListTileBar from '@material-ui/core/GridListTileBar';
 import ListSubheader from '@material-ui/core/ListSubheader';
 import IconButton from '@material-ui/core/IconButton';
 import InfoIcon from '@material-ui/icons/Info';
-// tslint:disable-next-line: no-relative-import-in-test
 import tileData from './tileData';
 
 const styles = (theme: Theme) =>

docs/src/pages/demos/grid-list/tslint.json

@@ -0,0 +1,6 @@
+{
+  "extends": "../../../tslint.json",
+  "rules": {
+    "no-relative-import-in-test": false
+  }
+}