fixed tests for flatfile-to-json.pl stripping cds features
remove brittle and mostly useless flatfile-to-json.pl.t test for number of classes in interval in json
fixed some test code in flatfile-to-json.pl that was looking in the wrong place for stuff in json - looks like json changed a bit and broke these tests
reverted 'fixed' unit tests for flatfile-to-json.pl that were testing JSON from src/perl5//Bio/JBrowse/Cmd/FlatFileToJson.pm instead of lib//Bio/JBrowse/Cmd/FlatFileToJson.pm. Wonder why there are two of these files.
added tests/code to flatfile-to-json.pl to remove introns before writing out JSON
added fixtures for testing support for VCF in flatfile-to-json.pl
merge all the things