fixes issue with unused imports of SafeMath in the models

src/core/ElasticDAO.sol

@@ -210,16 +210,9 @@ contract ElasticDAO is ReentryProtection {
    * must be sent in the transaction by the calling address
    * The token contract should be successfully be able to mint  _deltaLambda
    */
-  function join()
-    external
-    payable
-    onlyAfterSummoning
-    onlyWhenOpen
-    preventReentry
-  {
+  function join() external payable onlyAfterSummoning onlyWhenOpen preventReentry {
     Token.Instance memory token = _getToken();
 
-
     ElasticGovernanceToken tokenContract = ElasticGovernanceToken(token.uuid);
     uint256 capitalDelta =
       ElasticMath.capitalDelta(
@@ -255,7 +248,7 @@ contract ElasticDAO is ReentryProtection {
     require(success, 'ElasticDAO: Mint Shares Failed during Join');
 
     // return extra ETH
-    if(success && msg.value > deltaE) {
+    if (success && msg.value > deltaE) {
       (success, ) = msg.sender.call{ value: SafeMath.sub(msg.value, deltaE) }('');
       require(success, 'ElasticDAO: TransactionFailed');
     }

src/models/DAO.sol

@@ -4,7 +4,6 @@ pragma experimental ABIEncoderV2;
 
 import './Ecosystem.sol';
 import './EternalModel.sol';
-import '../libraries/SafeMath.sol';
 import '../services/ReentryProtection.sol';
 
 /**

src/models/Ecosystem.sol

@@ -3,7 +3,6 @@ pragma solidity 0.7.2;
 pragma experimental ABIEncoderV2;
 
 import './EternalModel.sol';
-import '../libraries/SafeMath.sol';
 import '../services/ReentryProtection.sol';
 
 /**

src/models/Token.sol

@@ -4,7 +4,6 @@ pragma experimental ABIEncoderV2;
 
 import './Ecosystem.sol';
 import './EternalModel.sol';
-import '../libraries/SafeMath.sol';
 import '../services/ReentryProtection.sol';
 import '../tokens/ElasticGovernanceToken.sol';
 

src/models/TokenHolder.sol

@@ -5,7 +5,6 @@ pragma experimental ABIEncoderV2;
 import './Ecosystem.sol';
 import './EternalModel.sol';
 import './Token.sol';
-import '../libraries/SafeMath.sol';
 import '../services/ReentryProtection.sol';
 
 /**