add executable
add pry
change class to module
require cli
ignore vcr fixtures
update README
GithubGist.file, GithubGist.read_file_contents, GithubGist.create_gist
specs for GithubGist.file
add VCR cassette in the #authenticate_client helper method
change GIST_URL TO GISTS_API_URL
GithubAuth.invalid_credentials
GithugGist.file_not_found
invalid credentials
GithubGist, when the file is not found
add authenticate_client vcr cassette