Update travis

Author: hadley

.travis.yml

@@ -1,16 +1,9 @@
 language: R
-sudo: required
-warnings_are_errors: true
-
-r_packages:
-  - rmarkdown
+cache: packages
+sudo: false
 
 r_github_packages:
   - hadley/staticdocs
-  - jimhester/covr
-
-before_script:
-  - sudo Rscript -e "library(stringi); stri_install_icudt()"
 
 after_success:
   - Rscript -e 'covr::codecov()'

DESCRIPTION

@@ -25,6 +25,7 @@ Imports:
     scales (>= 0.3.0),
     stats
 Suggests:
+    covr,
     ggplot2movies,
     hexbin,
     Hmisc,