Stats file updates & bug fixes

1. Changed stats output to .tsv
2. Updates to assemblyfind stats - read pipeline versions to infer assembly type
3. Added -f all option to assemblyfind - returns both contigs and scaffolds
4. Fixed issue with contigs and scaffolds going into the same stats file when the -f all option is selected
5. Fixed problem with abs_path returning undef values when symlink path has trailing / 
6. Bug fixed with how Filter.pm is finding stats files
7. All scripts now support symlinking to CWD
8. Updated tests to reflect these changes