Adding command line interface

[chrisgorgo]

Closes #43.

Usage: nimare [OPTIONS] COMMAND [ARGS]...

Options:
  --help  Show this message and exit.

Commands:
  ale

Usage: nimare ale [OPTIONS] SLEUTH_FILE

Options:
  --output_dir TEXT     where to put the output maps
  --output_prefix TEXT  common prefix for output maps
  --n_iters INTEGER     number of iterations for permutation testing
                        [default: 10000]
  --help                Show this message and exit.