fmp_splits() is broken (at least on R it is)

This:
```
library(fmpapi)
api_key <- '(my key)'
fmp_api_key(api_key)
readRenviron('~/.Renviron')
fmp_splits("IBM")
```

gives error:

```
Error in !is.null(arguments$endpoint) && arguments$endpoint == "company-outlook" : 
  'length = 2' in coercion to 'logical(1)'
```
