Build addons only when source or Node.js version changes

[braydonf]

Currently the addons are built on each install. This would be better to only build what and when necessary. Similar to gcc and other build tools, only build the necessary not already compiled portions if necessary. This may be somewhat limited to what is available from node-gyp. As a base, if the Node.js ABI version changes or the source changes, the addons will need to be rebuilt.