Pull in jackson 1.8.8

Jackson 1.4.2 would erroneously report that fields with long values were
of type int and truncate the value. This has been fixed by Jackson
1.8.8.
Move application of IndirectedDelayedExecutor to Engine build time
Remove superfluous EarlyFinishException constructors
Minor cleanup to EngineBuilder
Rename TaskLogImpl to TaskLogger

This change also removes the TaskLog interface, because we will not need
it shortly.

Conflicts:
	src/com/linkedin/parseq/BaseTask.java
Introduce PlanContext for plan-level configuration and facilities
Add tests for ArgumentUtil
Fix TestSeqTask.testSeq10
More tests for Promise listeners that throw errors
Fixes + more tests for AsyncCallableTask

- Doc purpose of tests
- Use time-bound waits
- Test for a wrapped callable throwing an Error
Prefer time-bound awaits for tests
Lift code for hiding system tasks