Check application configuration hash when requesting application conf…

…iguration (#11)

* - adds app config hash check

* - fixed unit tests

* - use updated em-app

* - returned back old fn name

* - code review changes

* - cargo fmt

* code review changes

* - usage of new type

* - updated em-client

* - updated em-client

* - use latest em-client

* - lock file after conflicts fix

* - update to use Sha256 type from em-client

* - update em-client crate

* - code review changes