Provides some much needed TLC

[allfro]

The following changes have been made:

• Changed build system to Gradle to make it cleaner and easier to extend
• Removed release files and created a simple build script to create all the release directories and Mac app/dmg
• Used dependencies from maven for javassist, postgresql, and msgpack
• Created a multi-module gradle project to produce two jars (cortana.jar and armitage.jar) which have different default entry points/classes
• Updated the sleep dependency to 2.1

This has been tested with metasploit-framework's latest branch and appears to work correctly. Next step will be to add unit tests at some point.