Restore CI cache, remove require bug info in readme

Author: cgewecke

README.md

@@ -116,11 +116,6 @@ MyContract.deployed().then(instance => {
   })
 });
 ```
-**Using `require` in `migrations.js` files**: Truffle overloads Node's `require` function but
-implements a simplified search algorithm for node_modules packages
-([see Truffle issue #383](https://github.com/trufflesuite/truffle/issues/383)).
-Because solidity-coverage copies an instrumented version of your project into a temporary folder, `require`
-statements handled by Truffle internally won't resolve correctly.  
 
 **Using HDWalletProvider in `truffle.js`**: [See Truffle issue #348](https://github.com/trufflesuite/truffle/issues/348).
 HDWalletProvider crashes solidity-coverage, so its constructor shouldn't be invoked while running this tool.

circle.yml

@@ -1,9 +1,6 @@
 machine:
   node:
     version: 6.11.0
-dependencies:
-  pre:
-    - rm -rf node_modules/
 test:
   override:
     - npm run test-cov