Error message incorrect after uploading wrong format file

[someren]

Describe the bug The error message which is shown after uploading a wrong format file is very unclear:

1. The colour of the text is blue instead of red or similar to other warnings (red background, white letters). As a result I did not see the error message the first time and only noticed it wasn't attached at the summary.
2. The text is incorrect. It shows three available formats: .jpeg, .png and .gif. However, I am also able to upload .jpg files. This format should also be included in the error message.
3. Additional: Please check on file size as well (see #125) and show a warning on the same location.

To Reproduce Steps to reproduce the behavior:

1. Go to 'Melden'
2. Click on 'Plus' at "Foto's toevoegen'
3. Choose a wrong file format like .pdf
4. See error

Expected behavior I expect a very clear warning or error message after uploading a wrong file format. I expect a correct error message I expect that it also checks on file size and not after submitting my signal

Screenshots

Desktop (please complete the following information):

• OS: Microsoft
• Browser Chrome

[someren]

Alternative: Increase the maximum upload size from 2/3 MB to 10-15MB. Pictures that are made on a smartphone are simply larger than a few MB...

[MauritsR]

I'm working on a fix for the first 2 issues. The 3rd point is discussed in https://github.com/Signalen/frontend/issues/125

[boris-arkenaar]

This seems to have been fixed now.