Include header files from kernel dir
Scheduler receives arch graph and return resources

With this, users can assign GPUs explicitly.
Add "time" property to scheduler

This property returns the executed time for a graph, e.g. the number that is
printed after the scheduler finishes.
Release version 0.6.0
Expose asynchronous two-way queue
Fix autotools build
Include two-way queue in top-level header
Add ufo_buffer_set_host_array
Update buffer location for user-supplied data
Add enhanced MPI support