Move model test classes to weiboclient4j.model package
Move AbstractParseJsonTest to model package
Add ParseWeiboErrorTest
Move PagingTest and ParametersTest to params package
Rename WeiboClient2 to WeiboClient
Introduce WeiboClient2 for backward compatibility
Modify CHANGES and README
[maven-release-plugin] prepare release weiboclient4j-0.4.2