clara virt memory and volume size should support units

[rezib]

Currently, the memory and storage volumes size are expressed in KiB. It is quite painful and error prone since its easy to forget or add a digit. The configuration file should support using units such as MB or GB, with a default in GB.

[mehdid]

I guess something like the following should do the work:

--- a/clara/virt/libvirt/volume.py
+++ b/clara/virt/libvirt/volume.py
@@ -36,6 +36,8 @@
 import logging
 logger = logging.getLogger(__name__)

+import humanize
+
 from clara.virt.exceptions import VirtRuntimeError

@@ -88,10 +90,10 @@ class Volume():
         return result

     def get_capacity(self):
-        return self.capacity_bytes
+        return humanize.naturalsize(self.capacity_bytes)

     def get_allocation(self):
-        return self.allocation_bytes
+        return humanize.naturalsize(self.allocation_bytes)

     def get_name(self):
         return self.name