Code cleanups.

ECLServerHandler.java:
Moved fields to the top of the file.
Extracted method asDate(), toString(CSN), isEligible(), debugInfo(), getNextMessage(), newECLUpdateMsg().
Renamed getNextEligibleMessageForDomain() to computeNextEligibleMessageForDomain().
Renamed initializeCLSearchFromGenState() to initializeCLSearchFromCookie().
In initializeChangelogDomainCtxts(), used foreach + extracted local variable "latestServerState" (no need to duplicate it) + collapsed one if statement.
Removed commented out code.

ECLServerWriter.java:
Minor code cleanup:
- Removed useless parentheses
- Collapsed if statements