pwclient: fix handling UTF-8 in patch info

pwclient: fix handling UTF-8 in patch info

This patch fixes following error when redirecting 'pwclient info' output:

---8<---
andreas@dockstar % pwclient info 295268 > /tmp/test.out
Traceback (most recent call last):
  File "/home/andreas/bin/pwclient", line 508, in <module>
    main()
  File "/home/andreas/bin/pwclient", line 471, in main
    action_info(rpc, patch_id)
  File "/home/andreas/bin/pwclient", line 242, in action_info
    print("- %- 14s: %s" % (key, value))
UnicodeEncodeError: 'ascii' codec can't encode character u'\xdf' in position 29: ordinal not in range(128)
--->8---

Signed-off-by: Andreas Bießmann <andreas@biessmann.de>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>