Opt in to trailing slash 307 redirect. Opt out of 405 logic.

[schloerke]

Fixes #100
Fixes #465

If a route is submitted without a trailing slash, and a comparable route exists with a trailing slash, then a 307 redirect is returned

options_plumber("redirect" = TRUE)

pr() %>% 
  pr_get("/get/", function(a) a) %>%
  pr_post("/post/", function(a) a) %>%
  pr_mount(
    "/mnt", 
    pr() %>% pr_get("/", function(a) a)
  ) %>% 
  pr_run(port = 8000)

$ curl "localhost:8000/mnt"
{"message":"307 - Redirecting with trailing slash"}

# follow redirect
$ curl "localhost:8000/mnt?a=42" -L
["42"]

curl "localhost:8000/mnt"
#> {"message":"307 - Redirecting with trailing slash"}

# follow redirect
curl "localhost:8000/mnt?a=42" -L
#> ["42"]

curl "localhost:8000/get?a=42"
#> {"message":"307 - Redirecting with trailing slash"}
curl "localhost:8000/get?a=42" -L
#> ["42"]

curl --data 'a=42' "localhost:8000/post"
#> {"message":"307 - Redirecting with trailing slash"}
#> ["42"]

PR task list:

• Update NEWS
• Add tests
• Update documentation with devtools::document()

---

• I am not sold on the new option names. Any ideas?
• Is it ok to bring in ellipsis?
• Is stopping ok if a bad option name is given or an unnamed option is given?
• Is ok to put ... at the beginning of options_plumber()?