Added several unittest for LXCHypervisor
oops
Add functions to perform disk image partition mapping

Added two functions to utils.storage namespace.
CreateDiskImageDeviceMapper will perform loopback device and
device-mapper device allocation and then provide block devices
to access each partition of disk image.
ReleaseDiskImageDeviceMapper is inverse function of
CreateDiskImageDeviceMapper.
Both of these functions assumes that kpartx(1) is installed.
Fix GetAllInstanceInfo of LXCHypervisor

Filter only .conf files to listing avaiable instances uniquely.
Fix GetAllInstanceInfo of LXCHypervisor

Filter only .conf files to listing avaiable instances uniquely.
Add a "stash" file functionality to keep required data during instance
life
Changed StartInstance behavior

- Make partition mapping before mounting rootfs if main storage is file-based storage
- Added CleanupInstance to perform required cleanup before exit or on error
- Write stash file to save required information for instance cleanup