Added IntRange min and max preview to --help output

[IamCathal]

Issue #1525 requested to have the following output for using the --help flag on options of type IntRange:

Usage: test.py [OPTIONS]

  Simple program that greets NAME for a total of COUNT times.

Options:
  --count INTEGER RANGE  Number of greetings.  [default: 1-32 inclusive]
  --help                 Show this message and exit.

This can be used like as a regular click user would expect it to:

import click

@click.command()
@click.option("--count",type=click.IntRange(1, 32), show_default=True, default=1, help="Number of greetings.")
def hello(count):
    """Simple program that greets for a total of COUNT times."""
    for _ in range(count):
        click.echo("Hello!")

if __name__ == '__main__':
    hello()