Be able to configure disperse (ec) volumes

[JohnStrunk]

Describe the feature you'd like to have.
In addition to having replicated volumes, it should be possible to provision erasure coded volumes via parameters.volumeType.type and parameters.volumeType.disperse.*

What is the value to the end user? (why is it a priority?)
Users may prefer to make the capacity/performance trade-off that is available with disperse volumes.

How will we know we have a good solution? (acceptance criteria)

• When parameters.volumeType.type has a value of disperse, an EC volume will be created
• parameters.volumeType.disperse.data can be used to change the number of data fragments, defaulting to 4
• parameters.volumeType.disperse.redundancy can be used to change the number of checksum fragments, defaulting to 2.

Additional context

• parameters.volumeType.type should default to replicate, not disperse

Ref: #30