Added EcardNote

According to Udayan's suggestion, added ECardNote class on Parse to
store relation between Alice and her collected cards. Entire table is of
the size of N*n.
1. Now Add button creates new object in ECardNote as well as add to
user's collectedIDs
2. Delete button deletes object from ECardNote and removes record from
collectedIDs
3. right now ECardIds are input as text in Add page, should be replaced
by QR scanner returned value
4. Everything compatible with offline Add new card!