lib/android: Improved documentation

Signed-off-by: Frédéric Vachon <fredvac@gmail.com>
lib/android: Added comments

Signed-off-by: Frédéric Vachon <fredvac@gmail.com>
lib/android: Renamed api1* to shared_preferences_api1*

Signed-off-by: Frédéric Vachon <fredvac@gmail.com>
lib/android: Corrected misspellings

Signed-off-by: Frédéric Vachon <fredvac@gmail.com>
lib/android: Added serialization tests

Signed-off-by: Frédéric Vachon <fredvac@gmail.com>
lib/android: add_to_preferences now redefines Serializable

Signed-off-by: Frédéric Vachon <fredvac@gmail.com>