Set default webroot parameter for Lemper CLI create subcommand

[joglomedia]

1. Current version 1.2.0 requires webroot parameter for defining user running virtual host.

Proposed suggestion:

Make the username parameter as optional, set default user to Lemper account, when username is not set, then use default username.

2. Current version 1.2.0 requires webroot parameter for defining web root directory, and aborting when it is not set.

Proposed suggestion:

Make the webroot parameter as optional, set default web root to /home/lemper/webapps/{domain_name} directory, when webroot is not set, then use default webroot.