fixed crossref parsing if no contributor exists, use first_name and surname
Merge remote-tracking branch 'origin/dev-crossrefContributorParsing'
added year column to counter event parsing
Merge remote-tracking branch 'origin/dev-addYearToCounterEvents'
handle missing publication type
Merge pull request #35 from articlemetrics/dev-crossrefMissingPublicationType

Handle missing publication type in crossref data