Hey, I was diagnosed with Crohns During my Sophomore year in undergrad and will be attending medical school next year. As others have said, don't let your condition define you, but try to be observant as to what foods effect you and what lifestyle changes help you manage your health... And finding the right medication is a must.
I have talked to quite a few doctors from various specialties (worked under a GI for quite some time) as well as ones on admissions committees about this, and all of them have been encouraging. My interviewers even seemed to respect me for disclosing my condition and talking about how it has motivated me towards a career in medicine and what it has taught me about bedside manner.
Remember these words above all others "You are not your disease!". Many people with chronic conditions begin to identify with their conditions more than anything else, and this is a slippery slope. Have hope.