RX + Retrofit preps

------- Dependencies -----------

//RX
    implementation 'io.reactivex:rxjava:1.3.0'
    implementation 'io.reactivex:rxandroid:1.2.1'

//Networking
    implementation 'com.squareup.retrofit2:retrofit:2.3.0'
    implementation 'com.squareup.retrofit2:adapter-rxjava:2.1.0'
    implementation 'com.squareup.retrofit2:converter-gson:2.1.0'
    implementation 'com.squareup.okhttp3:okhttp:3.10.0'
    implementation 'com.squareup.okhttp3:logging-interceptor:3.12.1'

-------Retrofit setup------------
//In activity
private lateinit var myAPI : ApiInterface

fun setupRetrofit() {
	 val okHttpClient = OkHttpClient.Builder()
            .addInterceptor(AuthHeaderReplacer(userStorage))
            .addInterceptor(TokenExpiredInterceptor(context, userStorage))
            .retryOnConnectionFailure(true)
			.build()
	val gsonConverter = GsonConverterFactory.create(GsonBuilder().create())

    val retrofit = Retrofit.Builder()
            .baseUrl(apiUrl)
            .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
            .addConverterFactory(gsonConverter)
            .client(okHttpClient)
            .build()
	myAPI = retrofit.create(BinelliRecorderAPI::class.java) // The parameter represents the Interface containing retrofit api calls
}

--------- API INTERFACE -----------------
interface BinelliRecorderAPI  {
@GET("case-categories")
    fun getCaseCategories(): Observable<CaseCategoriesResponse>
}

----------API CALL IN ACTIVITY WITH THE HELP OF RX --------------------

private fun getDepartmentsFromApi() {
            binelliRecorderAPI.getCaseCategories()
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe({
                    departmentsList.clear()
                    it.data.forEach {
                        departmentsList.add(it.name)
                    }
                    setupDepartmentsAdapter()
                }, {
                    showMessage(
                        mainScrollView,
                        unsuccessful_submission_view,
                        errorText,
                        apiErrorHandler.getError(this, it)
                    )
                    setupDepartmentsAdapter()
                })
    		}