Cover all nearcore features (missing from pynear)

[vgrichina]

Note, there is also other stuff that was not in pynear but we will very likely have:

• expiration_date Returns date and time of contract or access key expiration due to rent payments;
• add_access_key
• delete_access_key
• delete_account (Both delete_access_key and delete_account can be called by non-account owner if they are about to run out of balance due to rent)
• async_call (for contract calls the incur a long chain of cross-contract calls)
• async_status

Note, that some of these functions are or will be special cases of more generic functions. For instance, we discussed with @evgenykuzyakov and @ilblackdragon that we want all our transactions to look like function calls for consistency and forward compatibility. For instance, send_money will be a short cut for near call <my_account> send_money "

{"receiver": <other_account>}

", or somesuch.

_Originally posted by @nearmax in near/docs#36 (comment)

[behaviary]

These should be added to the NEP for near shell. near/NEPs#31.