message: added StoreClaimOffer command
diff: extern crate serde_json;
  +extern crate uuid;
  +use self::uuid::Uuid;
  use errors::anoncreds::AnoncredsError;
  use services::crypto::CryptoService;
  use services::pool::PoolService;
  @@ -109,20 +111,14 @@ impl ProverCommandExecutor {
  wallet_handle: i32,
  claim_offer_json: &str,
  cb: Box<Fn(Result<(), AnoncredsError>) + Send>) {
  - unimplemented!();
  -// let result =
  -// ClaimOffer::from_str(&claim_offer_json)
  -// .map_err(|err| AnoncredsError::CryptoError(CryptoError::InvalidStructure(err.to_string())))
  -// .and_then(|claim_offer| {
  -// self.wallet_service.set(wallet_handle, &format!("claim_offer {}", &claim_offer.issuer_did), claim_offer_json)?;
  -//
  -// Ok(())
  -// });
  -//
  -// match result {
  -// Ok(()) => cb(Ok(())),
  -// Err(err) => cb(Err(err))
  -// }
  + cb(self._store_claim_offer(wallet_handle, claim_offer_json));
  + }
  +
  + fn _store_claim_offer(&self, wallet_handle: i32, claim_offer_json: &str) -> Result<(), AnoncredsError> {
  + let uuid = Uuid::new_v4().to_string();
  + self.wallet_service.set(wallet_handle, &format!("claim_offer_json::{}", &uuid), &claim_offer_json)?;
  +
  + Ok(())
  }
  fn get_claim_offers(&self,
  