Merge pull request #18 from martinghunt/master

merge add_custom_ref_to_db
Merge pull request #19 from martinghunt/master

merge tidy_up_for_v0.4.0
Merge pull request #20 from martinghunt/master

Add test embl files
Merge pull request #21 from martinghunt/master

Die gracefully if cannot find reference
Merge pull request #22 from martinghunt/master

Change default QC percent identities to 80
Clean up unecessary files
Print all errors to stderr when syscall fails
Merge pull request #23 from martinghunt/qc_cleanup

Qc cleanup
Merge branch 'master' of github.com:sanger-pathogens/iva