update solc version of democracy

contracts/democracy/Delegation.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.21;
+pragma solidity >=0.5.0 <0.6.0;
 
 /**
  * @title Delegation

contracts/democracy/DelegationFactory.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.21;
+pragma solidity >=0.5.0 <0.6.0;
 
 import "./DelegationInterface.sol";
 import "./DelegationKernel.sol";

contracts/democracy/DelegationInterface.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.21;
+pragma solidity >=0.5.0 <0.6.0;
 
 import "../token/MiniMeTokenInterface.sol";
 

contracts/democracy/DelegationKernel.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.21;
+pragma solidity >=0.5.0 <0.6.0;
 
 import "../deploy/InstanceStorage.sol";
 import "./DelegationView.sol";

contracts/democracy/DelegationView.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.21;
+pragma solidity >=0.5.0 <0.6.0;
 
 import "./Delegation.sol";
 

contracts/democracy/Democracy.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.21;
+pragma solidity >=0.5.0 <0.6.0;
 
 import "../token/MiniMeTokenInterface.sol";
 import "./DelegationFactory.sol";

contracts/democracy/ProposalCuration.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.21;
+pragma solidity >=0.5.0 <0.6.0;
 
 import "../common/Controlled.sol";
 import "../token/MiniMeTokenInterface.sol";

contracts/democracy/ProposalManager.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.21;
+pragma solidity >=0.5.0 <0.6.0;
 
 import "../common/Controlled.sol";
 import "../common/MessageSigned.sol";

contracts/democracy/TrustNetwork.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.21;
+pragma solidity >=0.5.0 <0.6.0;
 
 import "../common/Controlled.sol";
 import "./TrustNetworkInterface.sol";

contracts/democracy/TrustNetworkInterface.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.21;
+pragma solidity >=0.5.0 <0.6.0;
 
 import "./DelegationInterface.sol";