Update copyright headers for consistency

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
Simplify the abc.ABCMeta handling code so that it's all in _abc.py

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
Ignore venv/ directory

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
Bump version to 0.6.1

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
Bump pyglibc version to 0.6.1

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
Fix signalfd's repr() method

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