change font encoding to utf8 for springer_article (#167)

* add Springer Journal template

* fix unknown "shaded environment" error

* make .bib file minimal

* remove assignment op

* add utf8 font encoding

* belated devtools::document() call

Author: strakaps

inst/rmarkdown/templates/springer_article/resources/template.tex

@@ -6,6 +6,7 @@
 %
 \usepackage{amsmath}
 \usepackage{graphicx}
+\usepackage[utf8]{inputenc}
 
 \usepackage[hyphens]{url} % not crucial - just used below for the URL
 \usepackage{hyperref}

inst/rmarkdown/templates/springer_article/skeleton/skeleton.Rmd

@@ -9,11 +9,11 @@ thanks: |
     end of the article.
 
 authors: 
-- name: Author 1
+- name: Äüthör 1
   address: Department of YYY, University of XXX
   email: abc@def
 
-- name: Author 2
+- name: Âuthóř 2
   address: Department of ZZZ, University of WWW
   email: djf@wef