You need to pass these in the headers, im no python programmer but according to http://docs.python-requests.org/en/latest/user/quickstart/#custom-headers
Your code for the get should be similar too:
url = 'https://api.twitch.tv/kraken/channels/129454141/subscriptions'
headers = {'Accept': 'application/vnd.twitchtv.v5+json', 'Client-ID': 'uo6dggojyb8d6soh92zknwmi5ej1q2', 'Authorization': 'OAuth cfabdegwdoklmawdzdo98xt2fo512y'}
r = requests.get(url, headers=headers)