add hierarchical tag viewer

[bbest]

Since the database uses a hierarchical data type ltree, we can show this in a viewer, like the listviewer R package.

# using the data from the jsoneditor simple example
#  in R list form

library(listviewer)

jsonedit(
  list(
    array = c(1,2,3)
    ,boolean = TRUE
    ,null = NULL
    ,number = 123
    ,object = list( a="b", c="d" )
    ,string = "Hello World"
  )
)

[Neil-Swanson]

@bbest @geocoug - started working through the tag heirarchy visualization. Not super pretty yet, but wanted to share the progress thus far.

Refer to the www_dev project splash branch: tag_viewer.Rmd