Installation docs are outdated

The documentation on installing NPanday is VERY outdated. We should just simply describe three ways:

• For Windows Developers: Install both NPanday build system and NPanday Visual Studio Add-in using the Windows Installer
• For Build-Servers or Mono developers:
• Bulk download and install all artifacts at once to the local repository
• Let Maven download from Maven Central
• Install from source (including installing the add-in from source)