Max width minimum value for images

[troughc]

This issue was found whilst testing #1202
In Artbi, the max width can be set to 0 and the ADMIN can save this setting. This should be disallowed in the software.

SUGGESTED MINIMUM WIDTH ALLOWED: 100 Pixels

Expected Behaviour

Add validation to back-end to expect a minimum of 100 pixels for maximum width.

And when the minimum amount is not entered, or the Max Width field is left empty:
English
CHANGE
Information is required
TO
A minimum value of 100 pixels is required.

French
CHANGE
Des informations sont requises
TO
Une valeur minimale de 100 pixels est requise.

[troughc]

@troughc add validation method and minimum number allowed for max width.

[sahalali]

@AbhishekPAnil Backend changes have been released. Please review this and move the ticket to the review phase.

[troughc]

Tested: PASSED