Steps to Reproduce:
1. Launch JIRA 4.0(using bamboo build 139 Trunk)
2. Login as project admin and edit the project.
3. Click on "Image" next to Project avatar to edit the image.
4. Try to upload a JPEG/PNG image.

Result:
1. It give error message "Errors
The file content you have provided is not a supported image format. Please try a JPEG, GIF or PNG file."
2. On Firefox you can upload the same image.

Expected:
1. User should be able to upload the image.