endianess fixes for #2318
pending fix verifcation from @juliantaylor

I started a build, powerpc is big endian
https://launchpad.net/ubuntu/+source/pandas/0.9.1-1ubuntu2
unfortunately some other component broke so its build dependencies are currently uninstallable, I'll retry it when its fixed.

the package also has python3 tests enabled, you might be interested in those results (as they currently fail)
ignore the scpy specfun failures, thats a problem in the scipy package
 the ppc build succeeded now, so the fix works fine, thanks
 merged. thanks!
