Data classes and other retrofit logic added

app/src/main/java/ru/vendetti/bitcoin_summarizer/RetrofitClient.kt

@@ -0,0 +1,16 @@
+package ru.vendetti.bitcoin_summarizer
+
+import retrofit2.Retrofit
+import retrofit2.converter.gson.GsonConverterFactory
+
+object RetrofitClient {
+    private const val BASE_URL = "https://api.alternative.me/"
+
+    val apiService: CryptoApiService by lazy {
+        Retrofit.Builder()
+            .baseUrl(BASE_URL)
+            .addConverterFactory(GsonConverterFactory.create())
+            .build()
+            .create(CryptoApiService::class.java)
+    }
+}