Fix #725 - enable disableNetworkCache by default

Author: roblourens

src/chromeDebugAdapter.ts

@@ -217,7 +217,11 @@ export class ChromeDebugAdapter extends CoreDebugAdapter {
                     evalResponse => logger.log('Target userAgent: ' + evalResponse.result.value),
                     err => logger.log('Getting userAgent failed: ' + err.message))
                 .then(() => {
-                    const cacheDisabled = (<ICommonRequestArgs>this._launchAttachArgs).disableNetworkCache || false;
+                    const configDisableNetworkCache = (<ICommonRequestArgs>this._launchAttachArgs).disableNetworkCache;
+                    const cacheDisabled = typeof configDisableNetworkCache === 'boolean' ?
+                        configDisableNetworkCache :
+                        true;
+
                     this.chrome.Network.setCacheDisabled({ cacheDisabled });
                 });