adding tests for issue #236.

* adding tests for display_pubkey(), display_amount() and transaction_confirmation() in tests/test_unit_tx.py.
* patching async functions.
* creating the patched.py module containing patched functions.
* modifying silkaj/tx.py to match patch requirements :
	* `from silkaj.wot import is_member` -> `from silkaj import wot`
        * `awit is_member()` -> `await wot.is_member()`