PY3: Fix error when applying salt state
PY3: Fix error when applying salt state

In Python 3, a command such as:

```
salt-call state.apply mystate
```

On certain SLS files (in my case a `py` rendered file) could yield an
error such as:

```
[ERROR   ] Data transport is broken, got: #!py
---SLS file contents here---
, type: str, exception: a bytes-like object is required, not 'str',
retry attempts exhausted
```

Change `RemoteClient.get_file` to ensure the `data` passed to `write` is
a `bytes` type in Python 3.

Signed-off-by: Sergey Kizunov <dfddabaa9af05982b01940b837a87844148069c9@ni.com>

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt