healthcheck: Need default value for url_path

[Senthilnathan Murugappan]

As of now if the url_path is not set for probe_type of HTTP, vrouter-agent asserts.
1) Would be better if we do param validation during healthcheck create in api server rather than asserting agent
2) Can we have default url_path as http://<IP of VMI>/ This way one can share a single healthcheck object across multiple VMIs and also one can pre-create healthchecks before VM is launched.

[OpenContrail Admin (ci-admin-f)]

Review in progress for https://review.opencontrail.org/16266
Submitter: Prabhjot Singh Sethi (<email address hidden>)

[OpenContrail Admin (ci-admin-f)]

Reviewed: https://review.opencontrail.org/16266
Committed: http://github.org/Juniper/contrail-controller/commit/c12c7466deb0a4230f68a4667eaab9d3011b6d56
Submitter: Zuul
Branch: master

commit c12c7466deb0a4230f68a4667eaab9d3011b6d56
Author: Prabhjot Singh Sethi <email address hidden>
Date: Mon Feb 1 16:12:02 2016 +0530

Fix Health Check HTTP url parsing

Issue:
------
usage of same variable name in local scope caused the
parsed value being destroyed with the scope, causing
url path to remain unset

Fix:
----
use http_parser to parse url provided for HTTP method,
where in case of error agent fall backs to use
http://<interface_primary_ip>/ as health check url

Closes-Bug: 1533606
Closes-Bug: 1533608
Related-Bug: 1530539
Change-Id: I60773eaef30b10008c693254de51933553b9561f