[Smtk-developers] Bump boost requirement to 1.60?

[David Thompson]

> Eventually C++ 2017 wil have filesystem in it - just cant wait that long - If we can’t use 1.60 then we will have to use kwsys (or write our own) - does everything build with 1.60?

SMTK and Remus certainly do. The only other packages that the superbuild says depend on Boost are ParaView and CMB. I haven't wiped my superbuild yet to try them because that takes a while... I will start it going before I take off.

	David