synthethic data for templates testing

[dkazanc]

Need to generate a synthetic dataset (probably using TomoPhantom) that would contain a variety of artifacts and also the ground truth data. Pack it into a single hdf file with the standard entry keys.

• 3D raw synthethic data
• synthethic flats and darks
• ground truth synthethic data
• ground truth phantom

Although templates testing can be done using the current test data, in future we would like to check the validity of the result. Arranging it now for #370 will help us to modify the tests later. Having the results of the tests loaded as images to Documentation page for each method will be greatly beneficial for users.