Added support for gzip compressed FITS files.
Added test for gzipped FITS files
Updated test directory entry counts in testcases
Made test file smaller
Added .fit to possible fits extensions
Added tests for .fit.gz and .fts.gz
Updated CHANGELOG
Only do regex match after gzip check has failed.
Used format instead of the old % syntax
Merge pull request #1135 from rubendv/gzip

[Review]: Added support for gzip compressed FITS files.