Missing CSP for media-manager

[nikrou]

When uploading a new image to media-manager, just after image is selected a csp report is thrown : blocked-uri: "blob"

To fix it, a data directive for "blob" is needed for img-src : Instead of

img-src:'self' data: media.dotaddict.org

It must be

img-src: 'self' data: media.dotaddict.org: blob:

p.s: I didn't find why but semi-column are mandatory.

[franck <carnet.franck.paul@…>]

(In [47b013a91ab9]) Add blob: to CSP img-src default directive, closes #2218