One time payment and upload

[amiyatulu]

Crust network need to provide a way for one time payment, and allow to upload and pin cids till the balance is over, both in api and crust files. Transferring fund every time through account is not ideal. Smart contract can lock the fund, and fund can only be used for storage. Master key with which funds can be withdrawn if user wants, and another key where upload can be done but can't withdraw the funds.