Rename 3 camelCase source version fields to underscore_spaced

[paynejd]

parentVersionUrl, previousVersionUrl and sourceUrl all need to be renamed to be underscore_spaced instead of camelCased. Change collections too if they are similar.

{
  'created_on': '2015-07-26T21:24:48.145',
  'description': 'Here is my description of this very exciting beta release that is just about nearly ready!!',
  'external_id': None,
  'extras': None,
  'id': 'v1.1.beta.2',
  'owner': 'CIEL',
  'owner_type': 'Organization',
  'owner_url': '/orgs/CIEL/',
  'parentVersionUrl': None,
  'previousVersionUrl': '/orgs/CIEL/sources/SNOMED-MVP/v1.1-beta/',
  'released': False,
  'sourceUrl': '/orgs/CIEL/sources/SNOMED-MVP/',
  'type': u'Source Version',
  'updated_on': '2015-07-26T21:24:49.421',
  'version_url': '/orgs/CIEL/sources/SNOMED-MVP/v1.1.beta.2/'
}

[paynejd]

@snyaggarwal Should this be addressed in oclapi2? (or has it already been?)

[snyaggarwal]

this was fixed