Release 0.20

• Add support for python3.6
• Debian 8 is the new default VM image
• FR-SD3 is the new default datacenter
• Update 'gandi mail create' command to allow passing password as parameter
• Update 'gandi certificate create' command: duration is now limited to 2 years
• Update 'gandi ip create' command to fix bad units in help message
• Fixes #182: 'gandi disk create' will detect datacenter when creating a new VM disk
• Fixes #184: 'gandi disk list' can now filter for attach/detach state
• Fixes #192: 'gandi certificate info' now still works after 500 certificates
• Fixes #201: 'gandi certificate export' was duplicating intermediate certificate
• Fixes #211: 'gandi paas deploy' tests should work again when using git commands
• Fixes a bug with options not using corrected value when deprecated
• Update unixpipe module to remove usage of posix and non portable imports