pep8 tidy up config

pep8 tidy up config

Enable the following warnings:

E126: continuation line over-indented for hanging indent
E131: continuation line unaligned for hanging indent
E203: whitespace before ':'
E221: multiple spaces before operator
E501: line too long
E722: do not use bare 'except'

These were originally chosen so that as much of the existing samba code
passed. With the intention of integrating PEP8 checking into build
process.  But the PEP8 output does not integrate into the known fail
mechanism, so this approach was abandoned.

setup.cfg is the default PEP8 config file having these exceptions
enabled means that new code can be added with those issues. Also tools
like pyls (python language server) use setup.cfg.

Disable the following warnings:

E402: module level import not at top of file
      Samba has a significant amount of code setting
      sys.path.insert(0, "bin/python")
W503: Line break before binary operator
      We need to have a preference, and PEP8 expresses a weak preference
      for disabling 503

Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Thu Dec 17 00:54:51 UTC 2020 on sn-devel-184