Refactor module loading API

Since the only one module exists in each player context at any given
time, move module loading from the Module class constructor to a
Player class method. This avoids a Module object having its contents
changed by a different Module object creation.

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Get sample data as byte array and add tests

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>