Optimize imports

Change-Id: I618171ab2a81279f61da719ced0317c719c40e49
diff --git a/NAMESPACE b/NAMESPACE
index 091ce17..4c3ff8f 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -27,25 +27,28 @@
 exportMethods(initialize)
 exportMethods(show)
 import(R.cache)
-import(dplyr)
 import(httr)
-import(jsonlite)
 import(methods)
-import(purrr)
-import(tidyr)
 import(utils)
 importFrom(broom,tidy)
 importFrom(dplyr,bind_cols)
+importFrom(dplyr,bind_rows)
+importFrom(dplyr,enquo)
 importFrom(dplyr,group_by)
 importFrom(dplyr,mutate)
+importFrom(dplyr,rename)
+importFrom(dplyr,rowwise)
 importFrom(dplyr,select)
+importFrom(dplyr,starts_with)
 importFrom(dplyr,summarise)
 importFrom(jsonlite,fromJSON)
 importFrom(lubridate,year)
 importFrom(magrittr,"%>%")
+importFrom(purrr,map_dfr)
 importFrom(stats,prop.test)
 importFrom(tibble,as_tibble)
 importFrom(tibble,remove_rownames)
 importFrom(tibble,rownames_to_column)
+importFrom(tibble,tibble)
 importFrom(tidyr,complete)
 importFrom(tidyr,expand_grid)