How to change mobile connections's DNS on Android KitKat?

I want to avoid censorship from my local mobile ISP (it blocks imgur, for example, for some unknown reason.

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I'm pretty certain that I can circumvent this by changing my DNS to Google DNS or OpenDNS, but I'm not really sure how to accomplish this on KitKat.

Info:
Device: Nexus 5

Android version: 4.4.2
Device status: rooted