Support for concurrent file operations.

Swith to using a regular service.
Perform file ops on thread pool.
Separate Job tests from service test.
Check in service test that wake lock is released and service shut down.
Increase copy buffer size to 32k (suggested by mtomasz).
Rework Copy testing to use an out-of-process provider (which has caused a content validation problem).
Move copy testing logic into base test and share it with Move testing.

Change-Id: I2f97d6c9f23c205b0f39ca6ba93bec119d63c80b