adopt slf4j in httpserver
fix: incorrect assert test
Changed more print statements to slf4j logging
Merge pull request #14 from walmartlabs/hash-apply-assertion-fix

fix: incorrect assert test
Converted more println to slf4j.
Convert println in messageServer to slf4j; covert some dummy log() function calls to slf4j; modify logging message wording
Merge pull request #16 from zheguang/master

Println to SLF4J
workaround: unit-test race between server and client start
Fixed StringOps comparison problem in attemptQueue