Docker-squash

Bug fixes
- For some images symlinks were not added back to the image, 111
- If a symlink was pointing to an existing location initially, add it back, do not try to cleanup it, 112

Bug fixes
- Better handling of symlinks that point to non-existing locations, 104
- Do not skip marker files when files in tar are prefixed with `./`, 108

Enhancements
- It is now possible to remove original image as part of squashing, use new `--cleanup` flag, 61

Bug fixes
- Whiteout entries for files from parent image lost by squashing, 97
- Hard links handling was rewritten, 99

Enhancements
- Exit with status code 1 on `KeyboardInterrupt`, 101

Bug fixes
- Hard links were not added back to the squashed image, now it's fiexd 94

Enhancements
- Added tests to run on Python 3.5

Bug fixes
- In cases, when the image is pulled from a v2 registry and then squashed the metadata was incorrectly prepared, 91

Enhancements
- It's now possible to save a tar and import into Docker daemon after squashing in one run

Bug fixes
- `UnicodeDecodeError: 'utf8' codec can't decode byte 0xc0 in position 4: invalid start byte` should no longer happen on Python 2, 76
- Executing squashing without specifying a name for the target image (`-t`) should not fail, 66
- Better hard links handling, 80

Enhancements
- Tar archive fetched from Docker daemon is no longer put into memory, instead it's fetched in chunks and written to the disk, 81
- Final tar archive is not created in memory, instead it's stored on the disk, 29