0.5.1: Added option to bootstrap stand without coping image

The option `--use-image-inplace` was added to run stands without coping
image.

0.5.0: Backups without downtime, S3 support

Backups:
The backup feature was significant reworked. It uses drivers approach
now. Two drivers added:
- Local backups of domains with QOCW2 disks.
- S3 backups of domain with QCOW2 disks.

The back method of domains were reworked to perform the procedure
without downtime so both drivers perform backups without downtime.

The new `start` option:
Added option `--start`. The option allows to specify start time for the
backup. The time format for the option is %H:%M:%S.

0.4.0: Added basic support of GZ images

Added ability to build images in the GZ(zlib) format. The compression
level is 5 by default.

0.3.0: Added ability to exclude directories in the dependency section

In build time all directory content is copied to an image but
it's not convineint sometimes. This change added ability to exclude
directories for dependencies:

```yaml
  deps:
    - dst: /opt/genesis_core
      path:
        src: ../../genesis_core
      # Exclude some directories
      exclude:
        - .git
        - .tox
```

0.2.8

Changed checksum file location for base image

0.2.7: Use valid parameters for flag options

Use correct parameters for `--oneshot` and `--no-wait` flags

0.2.6: Encryption of backups

Main improvement:
Added ability to encrypt backup:

Environment variables `GEN_DEV_BACKUP_KEY` and
`GEN_DEV_BACKUP_IV` is mandatory to encrypt the backup.
```bash
export GEN_DEV_BACKUP_KEY=secret_key
export GEN_DEV_BACKUP_IV=secret_iv

genesis backup --compress --encrypt
```

It works only with `--compress` flag

For decryption, use the `genesis backup-decrypt` command.
```bash
genesis backup-decrypt backup.tar.gz.encrypted
```

Other improvements and changes:
- Fixed #51 issue
- Fixes for documentation

0.2.5: Added ability to capture envs by wildcard

Added another way to pass environment variables to build time. It can be
done using wildcard `*`:

```yaml
  elements:
    # List of images in the element
    - images:
      - name: genesis-base
        format: qcow2
        envs:
          - GEN_USER_PASSWD
          - LOLO__*
```

All environment variables that are started from "LOLO" are captured and
passed to build image scripts.

0.2.4

Bugfix: Building several images for one element

0.2.3

Default values for environment variables