[scripts] add script to build and zybo project via xmd
[dev][cache] initial implementation of PL310 cache controller

-Hook into the arm cache flush routines
[platform][zynq] enable PL310 L2 cache controller
[app][tests] add quick n' dirty cache test routine
[include][compiler] add #define for OPTIMIZE attribute
[app][tests] add tests for floating point
[arch][arm] support for ARM floating point up through neon

-add code to undefined handler to trap arm/thumb vfp/neon instructions
-add infrastructure for enabling/disabling the fpu on v7 cpus
[arch][arm] Add vfp/neon context switching

Waits for a thread to trap a floating point operation, and from then
on out saves the fpu state.
[platform][vexpress-a9] enable floating point
[platform][zynq] enable floating point