Improved type mapping for enrich-type module (#7197)

Ticket was "Add more mappings for MDL type determination."
* Added default type to enrich-type module
  This allows individual providers to have default types for items
  whose types can not be determined.
  Also added default type of "text" to Minnesota profile.
* Removed test that asserts incorrect array for sourceResource.type
* Removed test that asserts that type gets removed, appended to format.
  This test asserts that sourceResource.type should get removed from
  sourceResource and appended to sourceResource.format, instead of
  being interpreted and translated to a valid type, within the
  enrich-type endpoint.
* Updated type conversion and created new module
  Created itemtype module for common type-conversion functions.
  Updated edan_to_dpla to use this new module.
  Updated enrich-type module to use this new module.
  Updated akara.conf.template to add some terms for MDC and to use
    the type-mapping configuration for enrich-type.