Renamed sol file with escrow beneficiaries

Renamed the file to ECDSARewardsEscrowBeneficiary.sol
Our etherum bindings code generator could not deal with the fact
RewardsEscrowBeneficiaries.abi does not exist and it was looking this
file because the beneficiaries were placed in
RewardsEscrowBeneficiaries.sol.

solidity/contracts/RewardsEscrowBeneficiaries.sol → solidity/contracts/ECDSARewardsEscrowBeneficiary.sol

@@ -2,20 +2,20 @@ pragma solidity 0.5.17;
 
 import "@keep-network/keep-core/contracts/PhasedEscrow.sol";
 
-/// @title ECDSABackportRewardsEscrowBeneficiary
-/// @notice Trasfer the received tokens from Phased Escrow to a designated
-///         ECDSABackportRewards contract.
-contract ECDSABackportRewardsEscrowBeneficiary is StakerRewardsBeneficiary {
+/// @title ECDSARewardsEscrowBeneficiary
+/// @notice Transfer the received tokens from PhasedEscrow to a designated
+///         ECDSARewards contract.
+contract ECDSARewardsEscrowBeneficiary is StakerRewardsBeneficiary {
     constructor(IERC20 _token, IStakerRewards _stakerRewards)
         public
         StakerRewardsBeneficiary(_token, _stakerRewards)
     {}
 }
 
-/// @title ECDSARewardsEscrowBeneficiary
-/// @notice Transfer the received tokens from PhasedEscrow to a designated
-///         ECDSARewards contract.
-contract ECDSARewardsEscrowBeneficiary is StakerRewardsBeneficiary {
+/// @title ECDSABackportRewardsEscrowBeneficiary
+/// @notice Trasfer the received tokens from Phased Escrow to a designated
+///         ECDSABackportRewards contract.
+contract ECDSABackportRewardsEscrowBeneficiary is StakerRewardsBeneficiary {
     constructor(IERC20 _token, IStakerRewards _stakerRewards)
         public
         StakerRewardsBeneficiary(_token, _stakerRewards)