Add command line flags

This adds the ability to override specific `liftoffrc` options from the
command line when running `liftoff`.

Available flags are:

    --[no-]cocoapods                 Enable/Disable Cocoapods
    --[no-]git                       Enable/Disable git
    -t, --indentation N              Set indentation level
    -n, --name [PROJECT_NAME]        Set project name
    -c, --company [COMPANY]          Set project company
    -a, --author [AUTHOR]            Set project author
    -p, --prefix [PREFIX]            Set project prefix
    -i, --identifier [IDENTIFIER]    Set project company ID (com.example)

Added ability to override all boolean & string liftoffrc config options with CLI arguments

Fixed string cli arguments

added indentation_level cli option

- renamed @liftoffrc to @options in Liftoff::CLI
- removed/renamed some CLI options
- moved liftoffrc/cli_options merging from LaunchPad to ConfigurationParser

dot on newline for multiline chained calls

cli: `project_name`->`name`, `indentation_level`->`indentation`

dot on newline for multiline chained calls

- removed separation comments in CLI
- renamed instances of "cli_options" and "cli_config" to just "options"