Updated titles to be Labels and not title case.
Removed files from required properties in dataset, #651
Give files a default empty array now it is no longer required
Updated the title for donor specific fields, to include donor in the title name.
Added barcode propertie to flowcell-details in replicate.
Added properties read length and read length units.
Removed second instance of alias in mixins.
Added aliases as identifying properites for these schemas.
Updated description for culture start date.
Added identifying properties. Also fixed adding aliases to required and moved to identifyingProperties.
Fixed adding aliases to required instead of identifying properties.
Merge branch 'master' into docs-update
Merge branch 'master' into readlength-666
Added default to read length units to be nt.
Mapping methods for Collection.
Return both added and removed keys from update_keys / update_rels
Add ALIAS_KEYS to Construct.
Script for updating keys and links after schema changes.
Merge branch 'construct-alias-685'

UPGRADE: Requires running a new script to update keys:

  $ bin/update-keys-links production.ini --item-type construct
Fix donors so they use the accession in their URL.