Adding `--open` option in `start/restart`, fixing #172

Open a url in the preferred application

Usage:

```sh
$ azk start -o [system]
```

help description:

```sh
$ azk help start

Usage: $ azk [options] start [options] [system]

Starts an instance of the system(s)

options:

  --verbose, -v, -vv  Sets the level of detail (default: false) - multiples supported
  --reprovision, -R   Force the provisioning actions before starting an instance (default: false)
  --open="", -o       Open a url of system in the preferred application
```
Merge branch 'hotfix/help_vm_201'
Merge branch 'hotfix/suggestion_rails_pid'
Updating `--open` option

Now the `--open` option in command start and restart open the default system.
Adding support to vbox in mounts folders.
Merge branch 'feature/cmd_open' into develop

Conflicts:
	CHANGELOG.md
	src/cmds/start.js
Fixing start agent
Update README.md

Added missing step for MacOS installation
Bumped version number to 0.8.0
Revert "Fixing start agent"

This reverts commit c1f28ce8c22b2a21839ef137faf2cf23c1035e34.
Fixing the commands that depend on the agent not to start it in scripts.
Fixing version for ssh2.
Adding `azk.version` in manifest templates.
Fixing configure to search and use sudo.
Fixing path to generate mac package in makefile.
Merge branch 'release/v0.8.0' into develop
Merge branch 'hotfix/readme' into develop