Add support for CTCP parsing - and use it a bit in log. TODO: create CTCP reply plugin
Several changes, formatting and function:

Formatting (to comply to guidelines):
- Replaces all calls of &str.to_string() with &str.into_string()
- Add semicolons after all return; statements
- Add commas after the last line in all match and struct statements

Function (to comply to guidelines):
- Use `pub use` instead of `use` for imports from pub mods in lib.rs
- Move load_configuration_from_file() to ClientConfiguration::load_from_file() to comply to guidelines

Function (other):
- Use Option when sending and receiving across tasks, so that we can have clean task ending when disconnecting from irc
- Use TaskBuilder to create tasks instead of just spawn(), so that we can name them meaningful names
- Add support for a message argument to the 'quit' command