allow using it as a library without spring framework (change to GdaxE…

…xchangeImpl)

src/main/java/com/coinbase/exchange/api/exchange/GdaxExchangeImpl.java

@@ -1,5 +1,6 @@
 package com.coinbase.exchange.api.exchange;
 
+import com.coinbase.exchange.api.config.GdaxConfiguration;
 import com.google.gson.Gson;
 import org.apache.log4j.Logger;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -49,6 +50,23 @@ public GdaxExchangeImpl(@Value("${gdax.key}") String publicKey,
         this.restTemplate = restTemplate;
     }
 
+    //Constructor that can be used without needing  spring library in calling program
+    public GdaxExchangeImpl(@Value("${gdax.key}") String publicKey,
+                        @Value("${gdax.passphrase}") String passphrase,
+                        @Value("${gdax.api.baseUrl}") String baseUrl,
+                        Signature signature) {
+
+        this.publicKey = publicKey;
+        this.passphrase = passphrase;
+        this.baseUrl = baseUrl;
+        this.signature = signature;
+        if(restTemplate == null)
+        {
+            restTemplate = new GdaxConfiguration().restTemplate();
+        }
+        this.restTemplate = restTemplate;
+    }
+
     @Override
     public <T> T get(String resourcePath, ParameterizedTypeReference<T> responseType) {
         try {