Add javadoc and allow the configuration of the min and max file upload sizes

Min: threshold memory to disk
Signed-off-by: Clement Escoffier <clement.escoffier@gmail.com>
Add javadoc to utility methods.

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

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

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

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