Added proxy configuration properties.

Constructor to send proxyCredentials to client creation.
Added support for ApacheHttpClientConfig

Proxy support using ApacheHttpClientConfig
added constants for Proxy Configuration
Update WnsClient.java
Added WnsProxyProperties
Added WnsProxyProperties
Added WnsProxyProperties
added dependency jars
Updated WnsProxyProperties as per the suggestions.
Updated WnsClient as per the suggestions.
Merge pull request #3 from harishankar-gopalan/master

Proxy settings for WnsService added.