[mdbci] Maria DB Continuous integration tool

# Raise: "Configuration name is required"
./mdbci public_keys

# 1. Generate node
./mdbci --template confs/mdbci_up_aws_test_config.json generate SOME_DIR
# 2. Up node\nodes (NOTE: maxscale.pem must be in mdbci directory).
./mdbci up SOME_DIR
# 3. Show public keys of node\nodes.
./mdbci public_keys --key maxscale.pem SOME_DIR
./mdbci public_keys --key maxscale.pem SOME_DIR/galera0

# Raise: "No such node with name galera123 in SOME_DIR"
./mdbci public_keys --key maxscale.pem SOME_DIR/galera123

# Raise: "Keyfile not found! Check path to it!"
./mdbci public_keys --key nowhere.pem SOME_DIR