v0.3.1

• Changed BufferFormatter::get_separator method signature.

Before:

fn get_separator(&self) -> &'static str;

After:

fn get_separator(&self) -> &str;

• Added new_owned and new_default methods for every BufferFormatter trait implementation.
• Implemented Default trait for every BufferFormatter trait implementation.
• Cover more code with tests.
• Improved examples section inside README file.