Merge pull request #6 from timotiirikka/master

Here's the VBPopBio.pm that passed the tests and modified GenotypeAssay.pm
Remove external_id as a public (JSON, API) attribute except for Project - use ->name instead.  protocol->description and experiment->description get/setter via props.  Multiprops are now 'add once'.  Refactored some duplicated code into Experiment->find_and_link_existing().
oops added some stuff I didn't mean to
refactoring Experiment loaders to reduce duplicate code and start handling descriptions etc
updated the ISA-Tab input for test 30 after major edits to the google spreadsheet
added study dates, publications, designs and more - SOME TESTS BROKEN
loading characteristics into multiprops for samples (but now easy also for assays)
now adding contacts in a limited fashion (limited by Chado)
removed organisms use in tests and Stock; new assay-stock types
genotypes loading nicely; added README new cvterms file
commentary added about collection site terms
phenotypes and protocol components are now loadable
much improved loading of geolocation and assay data
Added a small hack to allow multiple instances of the 'same' protocol parameter values - e.g. multiple insecticides and concentrations - see a_dual.txt sheet
assay performer and date fields loaded
ISA-Tab comments now loaded for assays and stocks as multiprops
Update api/Bio-Chado-VBPopBio/README-VBcv-terms-needed
Merge pull request #7 from topalis/patch-1

Update api/Bio-Chado-VBPopBio/README-VBcv-terms-needed
added new simple Bio::Chado::Schema script to populate cvtermpath for terms with a given dbxref prefix (rather than using the cvterm's cv.name)
docs