Add mavenization of pig-console jar and BasicP2LClient optionally works without LipstickPigServer

Mavenization
We're adding the pig-console jar as a dependency to one of our applications so we need a way to install it to our local repositories during development.  This is based upon gradle's documentation.  More that happy to change if there's a preferred method.

Removing LipstickPigServer requirement from BasicP2LClient
The goal is for everything to work without a LipstickPigServer.  The BasicP2LClient only needs the PigServer for gaining access to PigContext and the script cache.  We've made the BasicP2LClient rely only on a PigContext attribute, and handle the PigServer not being set.  This makes the LipstickPPNL function without the LipstickPigServer if it is given the PigContext and you are willing to for go the code being displayed in the web app (we have our own display of the code already).  It is also backwards compatible to still work with the existing LipstickPigServer.