add async and defer attributes to piwik.js
add async and defer attributes to piwik.js

inspired from http://piwik.org/docs/javascript-tracking/#toc-where-can-i-find-the-piwik-tracking-code
kennethlyn/pelican,rbarraud/pelican,Scheirle/pelican,UdeskDeveloper/pelican,ingwinlu/pelican,ls2uper/pelican,joetboole/pelican,lucasplus/pelican,Summonee/pelican,garbas/pelican,karlcow/pelican,karlcow/pelican,51itclub/pelican,janaurka/git-debug-presentiation,Rogdham/pelican,sunzhongwei/pelican,lucasplus/pelican,koobs/pelican,janaurka/git-debug-presentiation,deved69/pelican-1,treyhunner/pelican,eevee/pelican,11craft/pelican,ls2uper/pelican,GiovanniMoretti/pelican,iurisilvio/pelican,JeremyMorgan/pelican,kennethlyn/pelican,lazycoder-ru/pelican,kernc/pelican,rbarraud/pelican,deanishe/pelican,alexras/pelican,florianjacob/pelican,lazycoder-ru/pelican,levanhien8/pelican,douglaskastle/pelican,UdeskDeveloper/pelican,crmackay/pelican,getpelican/pelican,gymglish/pelican,ingwinlu/pelican,crmackay/pelican,florianjacob/pelican,avaris/pelican,number5/pelican,TC01/pelican,alexras/pelican,ls2uper/pelican,iurisilvio/pelican,catdog2/pelican,11craft/pelican,deved69/pelican-1,GiovanniMoretti/pelican,avaris/pelican,arty-name/pelican,51itclub/pelican,getpelican/pelican,farseerfc/pelican,treyhunner/pelican,JeremyMorgan/pelican,Scheirle/pelican,jimperio/pelican,joetboole/pelican,JeremyMorgan/pelican,talha131/pelican,jvehent/pelican,simonjj/pelican,kernc/pelican,justinmayer/pelican,ehashman/pelican,iKevinY/pelican,iurisilvio/pelican,Rogdham/pelican,btnpushnmunky/pelican,koobs/pelican,alexras/pelican,eevee/pelican,zackw/pelican,deanishe/pelican,sunzhongwei/pelican,joetboole/pelican,Scheirle/pelican,ehashman/pelican,TC01/pelican,zackw/pelican,11craft/pelican,jvehent/pelican,goerz/pelican,crmackay/pelican,0xMF/pelican,goerz/pelican,iKevinY/pelican,sunzhongwei/pelican,garbas/pelican,kernc/pelican,HyperGroups/pelican,jo-tham/pelican,deanishe/pelican,UdeskDeveloper/pelican,abrahamvarricatt/pelican,lucasplus/pelican,levanhien8/pelican,deved69/pelican-1,florianjacob/pelican,GiovanniMoretti/pelican,eevee/pelican,lazycoder-ru/pelican,rbarraud/pelican,51itclub/pelican,jo-tham/pelican,Summonee/pelican,simonjj/pelican,gymglish/pelican,abrahamvarricatt/pelican,TC01/pelican,ehashman/pelican,koobs/pelican,ionelmc/pelican,treyhunner/pelican,farseerfc/pelican,gymglish/pelican,kennethlyn/pelican,jimperio/pelican,Summonee/pelican,garbas/pelican,Rogdham/pelican,btnpushnmunky/pelican,douglaskastle/pelican,Polyconseil/pelican,number5/pelican,talha131/pelican,abrahamvarricatt/pelican,btnpushnmunky/pelican,catdog2/pelican,douglaskastle/pelican,jvehent/pelican,number5/pelican,Polyconseil/pelican,zackw/pelican,janaurka/git-debug-presentiation,catdog2/pelican,HyperGroups/pelican,sunzhongwei/pelican,HyperGroups/pelican,levanhien8/pelican,goerz/pelican,simonjj/pelican,karlcow/pelican,jimperio/pelican