Proxy for client side coverage collect

Changes:
1. change routerProxyConfig -> proxyConfig , move router config to "router" and add field "coverage" for client side coverage.
Details:
1. if client side code coverage set to true, then proxy will rewrite html by injecting some script to detect the test status. if test done (by check Arrow.testReport or check from proxy server) ,it will send back all coverage data.
2.big coverage data are send to proxy by xmlHttpRequest to avoid selenium server stack overflow.
3.Proxy server add handler for cross-domian problem.
other info are in docs/arrow_cookbook/arrow_in-depth/Code Coverage