Fix dependency scheme to be more granular

[cyrusv]

The two specific requests users have brought up:

• Start KSQL server and Kafka and ZK, without starting Connect or C3 (particularly useful to conserve laptop resources)
• Stop Connect without stopping KSQL server or C3 (Connect is not required for KSQL or C3 to run)

We decided to hard-code dependency declarations instead of using trees since bash doesn't suit tree structures well, and the dependencies should be relatively small and static.

We decided to automatically bring up ZK, Kafka, and Schema-Reg in most cases, and give more granular support in taking down services, to strike the balance between user control and convenience.

[cyrusv]

@kkonstantine new one against master: https://github.com/confluentinc/confluent-cli/pull/92