bugfix: save password with host in keyring

(the same way we try to recover it)
Add testcase
Merge remote-tracking branch 'origin/keyring_bugfix'

Fix #116
Fix failing testcase
Added passwordeval as an option for the general config section. If no password is provided the command provided as passwordeval will be called with username and hostname as arguments.
Renamed evalcmd -> command, use py.test's tmpdir, allow arguments in passwordeval option.
Fixed style.
Change exception to warning
Merge pull request #117 from vimbaer/passwordeval

New general config option: passwordeval
Add docs for passwordeval function
Change command error to warning

Also fix some smaller stilistic things
Rely on Python 3 to decode stdout.
Recommend system packages over pip

Including pkgsrc package by @0-wiz-0 and AUR package by @hobarrera.
Internal API and doc improvements
Merge branch 'outlook_fixes'
Add documentation for ``passwordeval`` parameter.
Version 0.3.0
Add tags feed
Add supported software
Add tests to distribution

See #119