add rx-ninja

[efueger]

Customer would like to use the https://github.com/w11k/rx-ninja TSLint rules.

• these are not currently included in the plugin's dependencies
• he's tried adding the rules to a folder in his repo, but we're seeing errors like:

Error: Cannot find module 'tslint'
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:636:15)
    at Function.Module._load (internal/modules/cjs/loader.js:562:25)
    at Module.require (internal/modules/cjs/loader.js:690:17)
    at require (internal/modules/cjs/helpers.js:25:18)
    at /code/node_modules/@w11k/rx-ninja/dist/bundle/tslint_rules/rxNinjaSubscribeTakeuntilRule.js:25:16
    at /code/node_modules/@w11k/rx-ninja/dist/bundle/tslint_rules/rxNinjaSubscribeTakeuntilRule.js:16:17
    at Object.<anonymous> (/code/node_modules/@w11k/rx-ninja/dist/bundle/tslint_rules/rxNinjaSubscribeTakeuntilRule.js:22:3)
    at Module._compile (internal/modules/cjs/loader.js:776:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:787:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)

Customer tried including the rules in his repo, but it looks like we'll need to add this to the plugin itself.

@tkqubo - does that sound like the right direction? Let me know if I can help with more details.