fix picard version comparison
Refactor to add test for Picard version selection and fix the version comparison
* Fix test plan
* add method to create comparable version object for bwa mem
* add method to deal with version of bwa mem other than 0.7.5a and 0.7.7
Explicitly test that the bwa versions compare correctly
switch to using parse for picard versions
remove vestigal comment
remove automated comments
actually use new errorrate version selector
Allow default vcf_description and vcf_id

It should be obvious when you are writing a report that something
needs to be filled in, otherwise, if you don't care it doesn't crash
Override field_descriptions instead of available_fields
Override field_descriptions instead of available_fields
Merge pull request #143 from ernfrid/bam_qc_picard_select

Bam qc picard select
Merge pull request #147 from apregier/backfill_required_methods

Backfill required methods