clean up context on build completion & add test

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
Add Daemon test utils

Docker-DCO-1.1-Signed-off-by: Tibor Vass <teabee89@gmail.com> (github: tiborvass)
hack/make: fix test-unit target to propogate TESTFLAGS properly

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Add TestDaemonRestartWithRunningContainersPorts

Docker-DCO-1.1-Signed-off-by: Tibor Vass <teabee89@gmail.com> (github: tiborvass)
Merge pull request #7765 from erikh/test_unit_testflags

hack/make: fix test-unit target to propogate TESTFLAGS properly
Merge pull request #7842 from unclejack/build_delete_context

clean up context on build completion & add test
Merge pull request #7191 from tiborvass/test-daemon

Add Daemon restart test along with Daemon utils
Use State as embedded to Container

Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com>
Merge pull request #7839 from LK4D4/embed_state_to_container

Use State as embedded to Container
Cleanup: Typo in job.go

Signed-off-by: Byung Kang <byungk91@gmail.com>
Merge pull request #7800 from djbk/master

Cleanup: Typo in job.go
move some io related utils to pkg/ioutils

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
pkg/ioutils: add WriteCloserWrapper

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
pkg/ioutils: add NewBufReaderWithDrainbufAndBuffer

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
pkg/ioutils: add ReaderErrWrapper to readers

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
pkg/pool: add pools for readers, writers & bytes

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
archive: use pooled bufio readers and writers

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)