I am in the same boat, I looked into policies carefully and asked my premed advisor.
You should be fine with one gap year (except at some low-tier schools, see the table posted earlier), but you will need to retake if you do two gap years.
The policies are that MCAT scores go stale after 2 or 3 years, and that is measured either from date of application or date of matriculation. Usually when you look at the whole policy, they are all pretty similar. 2 years from date of application at one school, 3 years from date of matriculation at another school, same difference. (Unless you deferred.) The fact that schools will give preference to the MCAT2015 is also a factor, but except for a few low-tier schools, the preference change for you (and me) will occur at the same time our scores go stale.
Anyhow, we should be fine with one gap year, and applying to begin in August 2017.