Fixed failing tests in NetcoreServiceTest and SunbirdWebPortalAdapterTest

[chinmoy12c]

Fixes: #28

[chinmoy12c]

Hey @pankajjangid05, we've moved the OkHttpClient outside and autowired it instead of creating an object ourselves. We have also set NETCORE_WHATSAPP_AUTH_TOKEN in the constructor instead of passing it from getInstance method. We need to test if everything is working fine with netcore. Also, we need to clean up the code to get NewNetcoreService instance using @service and autowiring it instead of using the getInstance method. Tracking it here: #30