Fix provider user/useradd: universal_options is array, not string

When I provision receipt with creating user many times it error:
```
Expected process to exit with [0], but received '2'
---- Begin output of ["usermod", "USERNAME"] ----
STDOUT:
STDERR: usermod: no options
Usage: usermod [options] LOGIN
```
It's because check universal_options in user provider. This options return array, but compare with string.