Resize vagrant disk storage (hard drive) with Virtual Box provider and Windows guest.

You need to know your VM name. It can be checked with:

> VBoxManage list vms
"YOUR_VM_NAME" {385e587a-ad47-4d36-a734-a126b9e04590}

Usually vagrant boxes comes with VMDK type storage which cannot be resized. 

You need to convert the format to resizeable VDI.

> VBoxManage  clonehd \

"/root/VirtualBox VMs/YOUR_VM_NAME/packer-virtualbox-iso-1459796137-disk1.vmdk" \

"/root/VirtualBox VMs/YOUR_VM_NAME/packer-virtualbox-iso-1459796137-disk1.vdi" \

--format vdi

0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%
Clone medium created in format 'vdi'. UUID: 67985552-a3e5-4fad-aedd-82565ac963d4

packer-virtualbox-iso-1459796137-disk1.vmdk is a hdd disk file. Your file name can differ slightly. 

packer-virtualbox-iso-1459796137-disk1.vdi is new disk file that will be created in VDI format.

Now it's time to resize the disk image.

> VBoxManage modifymedium \
/root/VirtualBox\ VMs/YOUR_VM_NAME/packer-virtualbox-iso-1459796137-disk1.vdi \
--resize 163840

0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%

163840 is new disk size in MB. Now you need to convert the disk image back to VMDK.

> VBoxManage  clonehd \
"/root/VirtualBox VMs/YOUR_VM_NAME/packer-virtualbox-iso-1459796137-disk1.vdi" \
"/root/VirtualBox VMs/YOUR_VM_NAME/packer-virtualbox-iso-1459796137-disk1.vmdk" \
--format vmdk
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%
Clone medium created in format 'vmdk'. UUID: 9f433356-976c-422b-b7f1-2e1279cec993


Run the VM (for example: `vagrant up`). In our case it is a Windows machine. 
That's why you need to go to the guest system and increase disk size there.
Open Disk Management `diskmgmt.msc`. Right click on allocated partition and click Extend Volume.