setup: fix typo

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
setup: include urwid.tests in packages

This allows 2to3 to correctly discover and patch all the modules in the
tests package. Without it running tests on python3 crashes

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
setup: PEP-8 fixes

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
urwid: widget: PEP-8 fixes

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
examples: subproc2: fix python3 compatibility

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>