This commit is heavily influenced by alacritty's source code. Using
`alacritty_config_derive` for deserializing the config file, and a
bare-bones logger using the crate `log`.

Our config file's filetype  has been switched from JSON to YAML as the latter
is more user-friendly. Extensive documentation has been added for each config field.
Those familiar with alacritty's config file should have no problem navigating
gallery_dlrs' config file.

The crate `colored` has been forked to add custom serde support.

Features added:

1. Add colors to logging.
2. Support for custom HTTP cookies.
3. Support for rotating logfiles.
4. User can choose between logging to stdout and stderr.
5. Override config options from the CLI with `-o`.

Features removed:

1. A custom logging format. As we switch from `log4rs` to a bare-bones logger,
   parsing custom logging formats is out of my programming capabilities.
2. Input files. Input files has been replaced with the CLI arg `-o`.

Other:

1. main.rs has been cleaned up significantly.
2. gallery_dlrs now initializes and runs in app.rs.
3. removed err.rs and now each module have their own error enum if neccessary.
4. job.rs code has been modified and moved to app.rs.