SCHEMA-150. Update CLI tools with support for composite keys.

 - Short fix to pretty-print entity IDs in "kiji ls".
 - InstanceBuilder supports composite entity IDs.
 - InstanceBuilder supports populating existing tables.
 - More unit-tests for kiji ls.
 - Reorganize kiji delete flags (--timestamp=latest|all|<ts>|upto:<ts>).
 - Split IntegrationTestKijiAdminTools into more focused, specific unit tests.