Add busy waiting mechanism
Test busy waiting
Update Aerotech motor for waiting mechanism
Add transitions to uca camera
Use magnitude in Dimax's readout
Add optional wait_on to wait for future in get/set

This makes it much easier to write wait dependencies, for example:

    future = None

    for device in orderered_devices:
        future = device.set_position(value, wait_on=future)
Add wait_on unit test
Make cropping in backprojectors more efficient
Remove keyword slice from ufo module
Add accumulate sink
Add test for accumulate sink
added "Expects" decorator
which describe expected arguments of process function
test for "Expected" decorator
Separate PCO cameras
Add Timestamp class for PCO cameras
Add PCO timestamp test
Make Travis happy
Simplify BCD decoding
Cleanup exceptions
Add regression test for #280