Fix test_swap test
Make acquisitions accessible as attributes

As a side-effect, make them read-only which keeps the list coherent for both
access types and restricts usage.
Add acquisition accessing tests
Merge pull request #288 from ufo-kit/install-acquisition-as-attribute

Install acquisition as attribute
Make FileCamera attributes available
Merge pull request #289 from ufo-kit/improve-filecamera

Make FileCamera attributes available
Don't assume dark_row is not None in backprojector
Don't skip so many tests

fixes #286 for now
Use straightforward way to return test results
Merge pull request #290 from ufo-kit/fix-nose

Don't skip so many tests
Don't skip Timestamp test by Travis
Import GLib when necessary for translating errors

Before the module was imported at class definition and not class instantiation
which is unnecessary because if the class is not instantiated we don't care that
its specific GLib.GError exceptions can't be converted to CameraError
exceptions.
Dimax doesn't yield None in readout_buffer
num_frames doesn't have to be a quantity in Dimax
Allow preparation and finishing of experiments
Add experiment prepare and finish tests
Merge pull request #291 from ufo-kit/prepare-and-finish-experiments

Allow preparation and finishing of experiments
Raise exception in uca if frame is unavailable
Dimax readout_buffer raises StopIteration
Merge pull request #292 from ufo-kit/fix-uca-grab

Fix uca grab