Jenkins ChangeSet for http://dev.digital-humanities.de/ci/job/link-rewriter/14/

Added a little documentation	by vitt
#src/main/java/info/textgrid/utils/linkrewriter/ImportMapping.java
Modified ImportMapping.add(…) to be URI-based	by vitt
#src/main/java/info/textgrid/utils/linkrewriter/ImportMapping.java