download, print, search options are getting hide when rows are selected.

## Expected Behavior

I have a requirement when we need to display action items( download, print, search, view columns) should be displayed even when rows fro the table are selected, maybe not all but Search, as a user should search and select the rows.

## Current Behavior
When the user selects the rows, the action items(download, print, search, view columns) are getting replaced with a number of rows selected message.

## Steps to Reproduce (for bugs)

1.Enable row selection and action items(download, print, search, view columns)
2. select rows from a table, see the action items fetting hidden behind no of rows selected message

## Your Environment

| Tech | Version |
|--------------|---------|
| Material-UI | 1.3.0 |
| MUI-datatables | ^2.0.0-beta.58 |
| React | 16.3.1 |
| browser | any |