[Docker plugin] Set default volume size

[Nicolas Gif]

Summary

Set default volume size

New Feature

Is seems default volume size is 16GB (I only tested with rexray/cinder). I found no way to specify it.

Version

8f5c80b1ec0e

Expected Behavior

Have a setting to specify default volume size as it exists for rexray-cli

Actual Behavior

Must specify -o size=<size> each time a volume is created.

Configuration Files

Please paste any related configuration files, such as /etc/rexray/config.yml
in this section. Please use the appropriate formatting when pasting YAML.
content. For example:

[
  "DOCKER_LEGACY=true",
  "REXRAY_FSTYPE=ext4",
  "REXRAY_LOGLEVEL=warn",
  "REXRAY_PREEMPT=false",
  "HTTP_PROXY=",
  "LIBSTORAGE_INTEGRATION_VOLUME_OPERATIONS_MOUNT_ROOTPATH=",
  "LINUX_VOLUME_ROOTPATH=",
  "LINUX_VOLUME_FILEMODE=",
  "CINDER_AUTHURL=https://auth.cloud.ovh.net/v3/",
  "CINDER_USERID=",
  "CINDER_USERNAME=xxxxxxx",
  "CINDER_PASSWORD=xxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
  "CINDER_TOKENID=",
  "CINDER_TRUSTID=",
  "CINDER_TENANTID=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
  "CINDER_TENANTNAME=xxxxxxxxxxxxxxxx",
  "CINDER_DOMAINNAME=default",
  "CINDER_DOMAINID=",
  "CINDER_REGIONNAME=GRA1",
  "CINDER_AVAILABILITYZONENAME=",
  "CINDER_ATTACHTIMEOUT=",
  "CINDER_CREATETIMEOUT=",
  "CINDER_DELETETIMEOUT=",
  "CSI_ENDPOINT=",
  "X_CSI_DRIVER=",
  "X_CSI_NATIVE=false"
]