Make error objects be made with 'new'

Invoking `Error` without `new` will add a new line `at Error (unknown source)` which is unnecessary and to some annoying.
 
```
alfred-nsh@google-api-nodejs-client:~/439948 (master) $ node -pe "throw Error('stuff')"                                                                                                                                                            
                                                                                                                                                                                                                                                   
[eval]:1                                                                                                                                                                                                                                           
throw Error('stuff')                                                                                                                                                                                                                               
      ^                                                                                                                                                                                                                                            
Error: stuff                                                                                                                                                                                                                                       
    at Error (unknown source)                                                                                                                                                                                                                      
    at [eval]:1:7                                                                                                                                                                                                                                  
    at Object.<anonymous> ([eval]-wrapper:6:22)                                                                                                                                                                                                    
    at Module._compile (module.js:449:26)                                                                                                                                                                                                          
    at evalScript (node.js:282:25)                                                                                                                                                                                                                 
    at startup (node.js:76:7)                                                                                                                                                                                                                      
    at node.js:627:3                                                                                                                                                                                                                               
alfred-nsh@google-api-nodejs-client:~/439948 (master) $ node -pe "throw new Error('stuff')"                                                                                                                                                        
                                                                                                                                                                                                                                                   
[eval]:1                                                                                                                                                                                                                                           
throw new Error('stuff')                                                                                                                                                                                                                           
      ^                                                                                                                                                                                                                                            
Error: stuff                                                                                                                                                                                                                                       
    at [eval]:1:7                                                                                                                                                                                                                                  
    at Object.<anonymous> ([eval]-wrapper:6:22)                                                                                                                                                                                                    
    at Module._compile (module.js:449:26)                                                                                                                                                                                                          
    at evalScript (node.js:282:25)                                                                                                                                                                                                                 
    at startup (node.js:76:7)                                                                                                                                                                                                                      
    at node.js:627:3
```