a news item for #1495 and add Jenny to contributors

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: knitr
 Type: Package
 Title: A General-Purpose Package for Dynamic Report Generation in R
-Version: 1.18.7
+Version: 1.18.8
 Date: 2017-11-26
 Authors@R: c(
     person("Yihui", "Xie", role = c("aut", "cre"), email = "[email protected]", comment = c(ORCID = "0000-0003-0645-5666")),
@@ -40,6 +40,7 @@ Authors@R: c(
     person("Jason", "Punyon", role = "ctb"),
     person("Javier", "Luraschi", role = "ctb"),
     person("Jeff", "Arnold", role = "ctb"),
+    person("Jenny", "Bryan", role = "ctb"),
     person("Jeremy", "Ashkenas", role = c("ctb", "cph"), comment = "the CSS file at inst/misc/docco-classic.css"),
     person("Jeremy", "Stephens", role = "ctb"),
     person("Jim", "Hester", role = "ctb"),

NEWS.md

@@ -10,6 +10,8 @@
 
 - Fixed rstudio/bookdown#501: the chunk option `out.height` can also take a percentage value when the output format is LaTeX (similar to `out.width`), e.g., `out.height = '30%'` means `.3\textheight` (thanks, @dataopt, #1482).
 
+- `imgur_upload()` starts to fail due to changes in Imgur's API (thanks, @jennybc, #1495).
+
 # CHANGES IN knitr VERSION 1.18
 
 ## NEW FEATURES