Don't import hap-nodejs directly, fix up some types, format code.

[tstordyallison]

• Stop importing hap-nodejs directly.
• Formatting & types cleanup.
• Add a build script and typescript dep.
• Remove yarn (lets stick to npm? It had both).
• Tested manually on homebridge 1.2 with a pair of cameras.

(sorry for the formatting, I did it without thinking and now I wish I had left it for a separate PR...).

[sponte]

Thanks for the contribution! I'll merge it now and release as 1.0.12