user service implemented to get a user id from a aaid.

if no user exists, a new one is created and the id is returned
return some JSON

header set at the beginning
basic ad service
a total count and a count per day are used instead of a single count
rules for the ad serving added
config file added
function to calculate a date
if and else inverted to have the smallest first
ad display conditions implemented
Merge branch 'ad'
comments updated
empty models added
module added to init a redis client
methods to create and fetch a user
user model used
ad model added
lines length
HTTP statuses added
no check done on the user
Merge branch 'models'