Angular 5 Compatibility Issue

[redbaty]

OpaqueToken has been replaced by InjectionToken

[laukotomi]

I added the files of the repository's src folder to my project as a module, replaced OpaqueTokens by InjectionTokens (there are only 2 use of it I guess) and it works fine.

However there is still a not-so-nice circular dependency in this module, because signalr.module.ts and signalr.ts are referencing each other. I fixed this too in my forked module, but I think it should be fixed in this module too.