Save mastery lookup to summoner. Added lookup for current mastery page.
adding to summoner test
Adding Runes
Change parameters to snake_case for consistency.
Call out 'current_mastery_page' in readme, as it's a cool feature
Change 'slot_id' and 'rune_id' to 'slot' and 'id', for simpler interface
Add test for runes
Bump version to 0.3.0