allow .avhdx files and add dismount to finally
allow .avhdx files and add dismount to finally

smaglio81/boxstarter,fhchina/boxstarter,fhchina/boxstarter,dex1on/pub,cam1985/boxstarter,dex1on/pub,dex1on/pub,tbyehl/boxstarter,modulexcite/boxstarter,tbyehl/boxstarter,dhilgarth/boxstarter,fhchina/boxstarter,napramirez/boxstarter,napramirez/boxstarter,dhilgarth/boxstarter,modulexcite/boxstarter,smaglio81/boxstarter,dhilgarth/boxstarter,tbyehl/boxstarter,modulexcite/boxstarter,napramirez/boxstarter,smaglio81/boxstarter,mwrock/boxstarter,cam1985/boxstarter,mwrock/boxstarter,cam1985/boxstarter