Improve report of disk-usage on minified versions
Improve report of disk-usage on minified versions

This patch makes disk-usage report little bit more useful.
Here's visual example of `du` vs ``du -sh`:

    % du jade.js jade.min.js runtime.js runtime.min.js
    76      jade.js
    40      jade.min.js
    4       runtime.js
    4       runtimeruntime.min.js

    % du -bh jade.js jade.min.js runtime.js runtime.min.js
    74K     jade.js
    40K     jadejade.min.js
    3.6K    runtime.js
    1.8K    runtime.min.js

cutsin/jade,flintinatux/jade,harp/jade,Mitrend/jade,gdibble/jade,martindale/jade,ceremcem/jade,andreytkachenko/jade,angrilove/jade,muthhus/jade,jjz/jade,harp/jade,illusionfield/jade,VANITAX/jade,mrotaru/jade,nyakto/jade-async,hnag409/jade,coderhaoxin/jade,ridixcr/jade,ridixcr/jade,colin-h/jade,fredyteheranto/jade,jirengu/jade,VeraWei/jade,omixen/jade,muthhus/jade,colin-h/jade,pugjs/jade,modulexcite/jade,webmasteraxe/jade,ddopson/jade-coffeescript,nyakto/jade-async,VANITAX/jade,jodytate/jade,derbyparty/derby-jade,webskyer/jade,illusionfield/jade,webskyer/jade,omixen/jade,cutsin/jade,fredyteheranto/jade,VeraWei/jade,rajnishyadav321/jade,webmasteraxe/jade,cgvarela/jade,pugjs/pug,Victorgichohi/jade,derbyparty/derby-jade,Victorgichohi/jade,mumaoxi/jade,pugjs/then-jade,modulexcite/jade,mumaoxi/jade,Laoujin/jade,cesarmarinhorj/jade,coderhaoxin/jade,rajnishyadav321/jade,gexiaowei/jade,Laoujin/jade,angryrobot/jade,cesarmarinhorj/jade,magicdawn/jade,jadejs/then-jade,pugjs/jade,timmfin/jade,ddopson/jade-coffeescript,cgvarela/jade,tranhieutt/jade,pugjs/pug,hnag409/jade,Mitrend/jade,gexiaowei/jade,slang800/yade,martindale/jade,magicdawn/jade,Shinchy/jade,angryrobot/jade,Shinchy/jade,bogus34/jade-vfs,jjz/jade,pugjs/then-jade,angrilove/jade,tranhieutt/jade,jodytate/jade,ilovezy/jade,wavii/jade,gdibble/jade,ilovezy/jade,andreytkachenko/jade,jirengu/jade,mrotaru/jade,jadejs/then-jade,bogus34/jade-vfs