Added Travis CI in anticipation of CRAN release.

Author: dtkaplan

.Rbuildignore

@@ -4,3 +4,4 @@ cran-comments.md
 ^README\.Rmd$
 ^README-.*\.png$
 ^NEWS\.md$
+^\.travis\.yml$

.travis.yml

@@ -0,0 +1,5 @@
+# R for travis: see documentation at https://docs.travis-ci.com/user/languages/r
+
+language: R
+sudo: false
+cache: packages

cran-comments.md

@@ -8,10 +8,9 @@ There were no ERRORs or WARNINGs.
 
 There was 1 NOTE:
 
-* checking dependencies in R code ... NOTE
-  Namespace in Imports field not imported from: 'R6'
 
-  R6 is a build-time dependency.
+  
+There are currently no downstream dependencies for this package
 
 ## Downstream dependencies
 I have also run R CMD check on downstream dependencies of httr 

tests/testthat/test-plots.R

@@ -8,5 +8,4 @@ mod_plot(mod1, ~ expend, bootstrap = 10)
 
 # Similarly, the confidence intervals aren't displayed nicely. We need to set `color = NA` when
 # there is just a single explanatory variable.
-mod_plot(mod1, interval = "confidence") %>%
-  gf_point(sat ~ expend, data = SAT, alpha = 0.5)
+mod_plot(mod1, interval = "confidence")