Add initial commit for caesar cipher project.
Add a spec for the offset_letter method.
Add an implementation of the offset_letter method.
Add a spec for the encode method.
Add implementation of encode method.
Update the naming of offset_letter to encode_letter, which will be nicely
complemented by a decode_letter method.
Add a couple specs for the decode_letter method.
Add the implementation for the decode_letter method.
Add more specs for the encode_letter method.
Add a spec for the decode method.
Fix a minor error in the recent spec.
Add an implementation for the decode method, passes specs.
Add a Usage section to the README to describe how to run this script for
encoding and decoding.
Add functionality to encode a file by default with default output file name.
Add the decode command line option and the functionality to decode an
encoded file.
Change the output file extension for encoded files from '.cc' to '.enc'.
Add command line option for specifying the name of the output file.
Clean up the code that handles option parsing and add some additional
comments.
Add a Solution section to the README.
Add a test task to the Rakefile.