Rename main lib file

To follow gem naming conventions, this renames flickr-uploadr to
flickr_uploader and its main class to FlickrUploader.
Add gemspec skeleton
Change bin file mode to 755
Remove .rb extension from bin file
Add bin file to gemspec
Move files.rb to lib/ folder
wip - refactor library
wip - read or create api file
Clean binary runner

This moves logic away from the binary runner and into the lib files for
better reuse.
Fix require statements

Add flickr_uploader lib folder to include path and fix the way the
binary file requires the lib.
Improve README and add installation steps
Setup bundler

Add necessary requires to use bundler within the app.
Read input from STDIN

This can be refactored in the future, but, for now, read user input from
STDIN to prevent errors when passing arguments to the executable.
Fix DOT_DIR name

Use ruby's standard Dir.home to get the current user's home directory
for the app's config files.
Refactor Uploader to extract client to own file

FlickrUploader::Uploader had client specific methods that did not belong
there.  This extracts all such methods into its own class to keep
concerns at a minimum.
Extract config file logic into ConfigFile class

The Client class had too many concerns regarding handling the config
file with Flickr authorization.  This extracts all that logic into a
reusable class that makes handling file contents easier.
Improve readability of DOT_DIR constant

Use ruby's native method to get the user's home directory to store
misc information when running the app.
Rename @auth_file to @auth_info in client.rb
Shorten verification code message
Shorten API key debug message