Facing issues with the API for using ggmap

Hi David,

After doing most of the things mentioned in posts related to this issue I am still getting this error.
My billing is enabled.
I installed the latest ggmap and ggplot2 (removed digest and rlang before that to have the latest version)

I have also checked: https://github.com/dkahle/ggmap/issues/235

```
devtools::install_github("dkahle/ggmap", ref = "tidyup", force=TRUE)
devtools::install_github("hadley/ggplot2")
library(ggmap)
library(devtools)
register_google(key = API_KEY)
map <- get_googlemap(center = 'India', zoom = 4)
```

_Source : https://maps.googleapis.com/maps/api/staticmap?center=India&zoom=4&size=640x640&scale=2&maptype=terrain&key=xxx
Error in aperm.default(map, c(2, 1, 3)) :
invalid first argument, must be an array
In addition: Warning message:
In get_googlemap(center = "India", zoom = 4) : HTTP 400 Bad Request_

Start by reproducing the reported register_google() and get_googlemap(center = "India", zoom = 4) calls from the issue, using the supplied Static Maps URL and HTTP 400 response as the focus. Trace get_googlemap's handling of that response and the subsequent aperm error; done means the failure is understood and the reported request behavior is addressed with appropriate verification.

Written by the indexing model from the issue text.