Add support for duration and size in bytes into the Configuration objects

Signed-off-by: Clement Escoffier <clement.escoffier@gmail.com>
fix some typos

Signed-off-by: Clement Escoffier <clement.escoffier@gmail.com>
Add a method in Configuration to check whether a value is contained into the configuration

Signed-off-by: Clement Escoffier <clement.escoffier@gmail.com>