every() depends on vector order when NA is present

``` r
library(purrr)

every( c(FALSE, NA), identity )
#> [1] FALSE
every( c(NA, FALSE), identity )
#> [1] NA
```
IMHO it should return the same and be consistent with &&:
``` r
FALSE && NA
#> [1] FALSE
NA && FALSE
#> [1] FALSE
```