Upgrade httpclient dependency

[LucaCinquini]

Because of known vulnerabilities, must upgrade the commons-http library to httpclient-4.5.1.jar

[LucaCinquini]

First of all, the httpclient dependency was removed from the old node-manager, which is not using it, rather using Hessian. Node-manager is a dependency for esgf-security.

[LucaCinquini]

Then, upgrade the httpclient dependency in esgf-security as such:

dependency org="org.apache.httpcomponents" name="httpclient" rev="4.5.1"