Squashes the pull request

Improvements to literature and testing

o Removes the class union in resource
  - As discussed this is not necessary

o Makes the bib Tex field editor a creator of the
  eml book and edited book

o Adds more tests for the literature module

o belongs to issue #27

Fixes the literature module coercions adds tests

o Fixes the book and edited book class coercions
o Adds more literature coercion tests

o Adds generic coercion for bib entries to citations

o Adds me as author to the package
Adds a warning

o When the coercion cannot determine the eml citation type
  then it is transfered to eml generic type
Merge pull request #85 from cpfaff/litrature

Improvements to literature and testing