Create help command

[Adam Connelly]

Create a help command that provides information about using the application. The command would have the following usage:

dbversion help [command]

If no command is specified the usage for the application should be printed along with the available commands. If a command is specified then information about that command should be printed.

[Adam Connelly (adam-rpconnelly)]

I've added the help command to dbversion. If the command is specified with no parameters, the output looks like:

./dbversion.exe help
  create Creates or upgrades a database using the specified archive.
  help Displays information about using the application and then exits.
  version Displays version information and then exits.

  Use dbversion help [command] for more help on a command.

If a command name is specified after help, the options for the command are shown like:

./dbversion.exe help create
Usage: dbversion create [options]

Options:
  -a, --archive The archive to create the database from.
  -c, --connectionString The database connection string.
  -v, --version The version to create or upgrade to.
  -p, --connectionProvider The hibernate connection provider.
  -d, --driverClass The hibernate driver class.
  -l, --dialect The hibernate dialect.