[LNT] Python 3 support: requests.response as text

[thopre]

Summary

lnt admin rm-machine command prints output from the REST API for
deleting machine line by line using requests.response's iter_lines()
method. However in Python 3 this method returns data by default and
printing expects a string. This commit uses the text attribute for
requests.response and iterate over the lines with splitlines.

[PrzemekWirkus]

LGTM but someone else must approve.

Note: this is trivial and should just go in.

[thopre]

Committed as bf6972e76492a73165ddfa68c16c777e8211449b

lnt/lnttool/admin.py

 def action_rm_machine(config, machine):
     """Remove machine and related data."""
     _check_auth_token(config)
 
     url = ('{lnt_url}/api/db_{database}/v4/{testsuite}/machines/{machine}'
            .format(machine=machine, **config.dict))
     response = config.session.delete(url, stream=True)
     _check_response(response)
-    for line in response.iter_lines():
+    for line in response.text.splitlines():
         sys.stdout.write(line + '\n')
         sys.stdout.flush()
 
 
 @click.command("rename-machine")
 @_pass_config
 @click.argument("machine")
 @click.argument("new-name")