Add additional artist_specs due to missing issue with podcast creation. Delete custom date validator, it was invalidating valid datetime. instead add validate_datetime gem. Now system works as needed. Also create basic layout of artist show page
Refactor aritst code, and extract artist and podcast generation functionality to concern
Add indices in podcasts table for :guid and :aritst_id field. Finish intial stage of artist show page creation
Refactor artists show page by taking out podcasts rendering logic into partial
Add extra tests to check correctness of artist show page