fix templatetag for no fractional bytes

In django 1.6, testing 0.0005 MB fails due to rounding issues.

Since a fractional byte makes no sense, just casting the float
value to an int.

Partially-implements: blueprint django-1point6
Change-Id: Id82faf32f0670f6342dac87a08affc10c7fda8de
Merge "fix templatetag for no fractional bytes"