Move some unit tests from TraP to PySE

[HannoSpreeuw]

There are nine files with unit tests in the test_accessors folder in TraP:

• test_aartfaaccasatable.py
• test_amicasatable.py
• test_casatable.py
• test_detection.py
• test_fits_accessors.py
• test_fitsblob.py
• test_kat7casatable.py
• test_lofarcasatable.py
• test_pickle.py

Move tests to PySE that were removed in:

• Separate pyse tkp#619
• Remove more remnants from PySE tkp#620

Blocks

• Reimplement DataAccessor for easier testing & validation #53

[HannoSpreeuw]

Duplicate of #64