Setting the Content-Type on the files.

Uses MIME::Types to guess what content type to set on the file and set it on the bucket.
This provides more hints to the browsers on how to render contents...
Merge pull request #4 from willkoehler/add_cache_headers

Set cache-control and expires headers to improve browser caching.
Merging master in.

Also setting the cache control on updated files.
Merge pull request #5 from fredjean/mime-types

Setting the Content-Type on the files.
Adding Will Koehler to the list of contributors.

Also bumping version to 3.0.7
adding pry for debugging purposes...
Adding a --force option to push all the files to S3.
Only override the options.force message if it is set on the command line.
Minor clean up.
Implemented support for a caching policy.
Small adjustment to the header.
Updated README, includes information on how to
force push to S3 and how to set headers.
Adding a prompt before the command.
Adding more information on caching.

Might make a good start of a blog post...
Fixing the table.
Bumping version in prep for releasing the next version of the gem.
Requiring Map.
Bump version.
Refactoring how the list of files to process is built and processed.
Add a --bucket command line to allow configuring an alternate destination bucket.

fixes #2.