Edit notification email for evaluation init

[jbenito]

Hello, 
This is the result of a test I did, using the automatic notification tool when the evaluation starts. 
The text is a bit too dry and impersonal to motivate people to complete the survey. Furthermore, the link goes directly to the survey, while there is an announcement page, which can give explanations on how to complete the form, and what will be done with the results. 
Hence, 2 suggestions for improvement : 
- make this message editable 
- link to the announcement page, rather than to the survey itself (or give the choice) 
For this time, we will not use the tool and send the people a message in another way. 
Together with the other remark I made, enlarging the type of questions that can be asked, this is potentially a very powerful feature. 
Thanks, 
Erwin