organizing calls

based on this commit: https://github.com/ChickenKyiv/loopback-tutor-intern-8/commit/17164e7e81cd34f0381082a823ea5c3fce2943e9

I think we need to split our conversation into two big topics:
1) moving api urls into a separated functions/methods, so it'll make our live easy when some routes will be changed
2) updating code at api-sample file and maybe moving it as separated package. because we'll use a same logic at other projects too, so i think it's a better way than just copy-paste.