(maint) Update rpm packaging to use updated boost

We've changed how we build boost. We are now building both pl-libboost
as well as pl-libboost-devel. This will allow us to unstall the minimum
number of files on a production system.
Merge pull request #178 from melissaanne/maint/build-with-pl-libboost-devel

(maint) Update rpm packaging to use updated boost