Added tests for PROBA2's SWAPMap.
1. Downloaded four fits files for SWAPMap and placed them in sunpy/data/test/SWAP folder.
2. Resampled and saved each of the fits files with 100x100 dimensions to reduce size.
3. Changed test_tables.py:test_entries_from_dir() to reflect the new additions to the test directory.
4. Ran tests and passed.