Remove unused tuples folder.

Review: https://reviews.apache.org/r/26152
Fixed AllocatorTest.SlaveLost test.

Review: https://reviews.apache.org/r/26163
Updated documentation/flags regarding new default hostname semantics.

Review: https://reviews.apache.org/r/26185
Synced container network configurations with host network
configurations.

Review: https://reviews.apache.org/r/26197