Disable the save button when no change has been made

Context

The save button appears on feature pages.

It's colour remains the same before and after saving, hence the user does not have a clear indication that there are

-> Changes to save

-> That the save has been effective 

To Do 

-> When there is nothing to save : Render the save button in another colour (light grey) 

-> When there is something to save : Render the save button in blue, as currently the case

 
Testing 

I will test different saving across different features, including with different 'commit preferences'