Give byte count units a uniform width

The new sbFormatBytes directive formats a byte count using the
humanReadableFilter and wraps the unit in a <span class="unit">
element.

This element is then given a minimum width to ensure that all units
take up at least this space (otherwise 'B' take up significantly less
space than 'KB' or 'MB').
Set width on size and count columns
Rename humanReadableFilter to bytesFilter

This is more in line with other AngularJS filters.
Simplify sbFormatBytes by using template over jQuery
bytesFilter: try parsing input as a number before rejecting it

Before, a string like "123" would have been returned unchanged. It is
now also processed as the number 123.
bytesFilter: test that 1000, not 1024 is used as base unit
Merge pull request #7 from mgeisler/set-column-widths

Set column widths