You can certificate your QMS by ISO 9001:2008 until September of 2015, after that you are allowed to do recertification in next two years.
After September 2018 you cn only be certified against ISO 9001:2015
I think there will be 3 year transition period, which means you can do the initial certification of ISO 9001:2008 by the end of august 2015 and then you can do surveillance audits until 2018 when you'll have to do recertification against 9001:2015.Auditors will be required to audit only to ISO 9001:2015 a year before ISO 9001:2008 expires. If things stay on schedule and ISO 9001:2015 is published in September 2015, as of September 2017 auditors will not be able to audit to the old standard, ISO 9001:2008.