Improves coercion in literature types

o Now the article has a working coercion article <-> bibentry
o Adds first coercion from book -> bibentry

Belongs to issue #27
fixed typo in a slotName
fixed coersion person to individualName: person needs S3 slot referencing
fix a few typos, example should actually run
add convenience function for constructing eml responsibleParty types
define concatenate methods for all ListOf classes; closes #67
create a packageId in eml prototype
includes a test case to make sure this doesn't overwrite identifiers read in when coercing XML to S4
eml_read gets the namespaces from the file, rather than the default namespaces
updated documentation
update roxygen, avoid error of '@' used in email
remove depricated test
add id get method to read example list
docs
rearrange definitions, depricate and prepare to depricated outdated methods
method for generating keywordSet node from list
updated documentation
Further improvements to the literature coercions

o Belongs to issue #27
Merge pull request #75 from cpfaff/litrature

Litrature module improvements: working on coercions between bibentry and eml