show limit summary in GB

Prior this change RAM in limit overview would be shown in MB,
but it makes sense to change this to use variable sizes.
This change also introduces to show 1 decimal position for sizes
shown in float (earlier it was zero).

Fixes bug 1223856

Change-Id: I243c9ea1616bc2684911b5d7d9399b4c3ee4aacd
Merge "show limit summary in GB"