[GUI] Make fragment size of preset configurable through GUI

[openvstorage-ci]

From @kinvaris on August 18, 2016 9:33

Currently we have to create a preset through the CLi if we want another fragment size.
In the GeoScale perspective, it would be interesting to make the fragment size of the preset configurable during creation/update.

Copied from original issue: openvstorage/framework#819

[openvstorage-ci]

From @domsj on August 18, 2016 9:43

FYI: updating the fragment size of an existing preset is currently not supported by alba.
If you need that (and maybe allow updating compression/encryption/name and others(?) too while at it): please file a ticket for alba too.

[openvstorage-ci]

From @domsj on September 14, 2016 15:6

This is important for global backends: you definitely want a bigger fragment size there.

[wimpers]

Fragment size can already be set through the API (#233). Not exposed in the GUI.

[khenderick]

API implementation by #233, packaged in openvstorage-backend-1.7.4-rev.736.e21c2bb