PDF viewer

- currently using ng-pdfviewer from https://github.com/akrennmair/ng-pdfviewer/
- pdf links now opens new tab and display the pdf within a new
AttachmentPDFController
- The preferred way of displaying the pdfs is inline with the other
content, especially for the judgement page. However currently this
library only allows us to display one pdf per page. A fix has been
made but has not been pulled into the master branch of the library.
https://github.com/akrennmair/ng-pdfviewer/pull/8