Make tests executable
Refine startup arguments + binary lookup

1. BINDIR (default: ../../src) is temporarily added to the PATH
2. Use env vars BITCOIND and BITCOINCLI, if set
3. Otherwise fall back to mastercored, mastercore-cli

This should cover manual use as well as automated builds.
Seperate tests of supported/future scenarios

- run_tests.py should be used to test mcore-0.0.9
- run_future_tests.py should be used to include meta DEx tests
Traditional DEx tests: don't require commit fee

There should be explicit tests of commit fees. (TODO)
Fix Simple Send final balance check typo