Added base extractor class
added soundcloud extractor class

Signed-off-by: arghdos <arghdos@users.noreply.github.com>
added soundcloud test

Signed-off-by: arghdos <arghdos@users.noreply.github.com>
added band camp extrator

Signed-off-by: arghdos <arghdos@users.noreply.github.com>
added band camp test

Signed-off-by: arghdos <arghdos@users.noreply.github.com>