fix the issue that tick tuple cannot work with system bolt
logviewer tries to determine log directory via logback configuration, falls back to storm.home/logs
use File methods to construct paths
Do the worker HB timeout check when HB's are updated
Fix sys stats cookie being lost from UI requests
Replace wrapper helper around core UI app

This will once again wrap cookies, sessions, etc., in a proper way.  See
compojure.handler/site.
add logviewer.appender.name config
logviewer locates log directory via appender named in storm config

exits on startup if it can't find the appender
throw RuntimeException and remove unnecessary System/exit
clearer arg name
Merge pull request #706 from d2r/d2r-nimbus-hb-check-timeout-on-update

Do the worker HB timeout check when HB's are updated
Merge pull request #702 from xumingming/fix-system-bolt

fix the issue that tick tuple cannot work with system bolt
Update README.md with list of Apache committers (#721)
add shell bolt pending limit in fresh branch
remove instanceof check
update README.md with Apache mailing list info
fix typo in the dev subscribe links
fix typos
Merge pull request #705 from strongh/logview-logback

logviewer tries to determine log directory via logback configuration
Merge pull request #730 from xiaokang/limit-shell-pending

add config to limit ShellBolt internal _pendingWrites queue length