Reorder R dependencies to not install packages before their dependencies

Workaround for #2, but currently each time this list is regenerated
by scan_r_dependencies.R, the reordering is lost

Author: mlell

scripts/gen/r_deps.txt

@@ -5,9 +5,9 @@ utf8         1.1.3
 colorspace   1.3-2  
 assertthat   0.2.0  
 rlang        0.1.6  
+crayon       1.3.4  
 cli          1.0.0  
 pillar       1.1.0  
-crayon       1.3.4  
 viridisLite  0.3.0  
 R6           2.2.2  
 labeling     0.3    
@@ -17,9 +17,9 @@ RColorBrewer 1.1-2
 Rcpp         0.12.15
 lazyeval     0.2.1  
 tibble       1.4.2  
+plyr         1.8.4  
 scales       0.5.0  
 reshape2     1.4.3  
-plyr         1.8.4  
 MASS         7.3-48 
 gtable       0.2.0  
 digest       0.6.15