Add support for ISBN-10 and ISBN-13 codes

This commit adds support for ISBN-10 and ISBN-13. Codes are generated as
per the ISBN-10 and ISBN-13 check calculation rules. This commit also adds
two unit tests to test the functionality.
Merge pull request #25 from isadaqah/isaac/isbn_code

Add support for ISBN-10 and ISBN-13 codes
using randomservice in the code class
Merge branch 'master' of git@github.com:DiUS/java-faker.git

Conflicts:
	src/main/java/com/github/javafaker/Faker.java

Signed-off-by: Richard Jaldin L <richard.jaldin@trueforce.com>