Merge pull request #820 from rm2342/master

Juris.js: changed adding of notes/additional metadata to comply with behaviour of beck-online.js
New translator: SAGE Knowledge
[ScienceDirect] ISBN/ISSN cleanup. Improved author/editor handling
Re https://forums.zotero.org/discussion/42733/sciencedirect-annual-serial-book-section-v-journal-article/
[SAGE Knowledge] Minor tweaks. Closes #810
[SAGE Knowledge] Fix name suffixes
[RIS] Fix non-standard Y1 date handling
Update T&F tests
[AEA Web] Fix multiples list
Adjust priorities for recent translators
As per https://github.com/aurimasv/translators/commit/5b4ef451a9c3c14fa9b2b8d5bce37a8bf7c1a3f2
[beck-online] Adjust target regexp to allow proxy detection
[Google Books] Use relative URLs