Fixes to failing tests of the database package

tl:dr: This PR fixes 9 tests.

This PR fixes all 9 tests that have failed in the last travis builds. There were two "types" of failing tests: The first category contains all tests which (indirectly) called ``entries_from_dir`` which calls ``sunpy.io.file_tools._detect_filetype``. This function changed the behaviour in the commit https://github.com/sunpy/sunpy/commit/7b9fd51269a425fc6c7abdf2d3caa09bb25b504a#diff-a8df63151f5d6a7dbbb55c07ffe37edeL144 by returning strings instead of modules. The other tests have failed because the VSO has changed: new data has been added in the timeframe I used for testing.