Merge pull request #45 from filinep/master

Server and worker errors
Various changes and bug fixes

-Added JAR hashing to prevent multiple copies of jar files in the database
-Added a node health status reporter (cpu, memory, disk space)
-Fixed a bug that prevented jar removal messages from being sent to workers
-Added a setting to control the progress update interval on workers
-XML files are now parsed on the client before the job upload process starts
-The upload no longer crashes when it receives invalid xml files
-Fixed an exception reporting bug in the worker

Signed-off-by: pleiades <pleiades@pleiades1.cs.up.ac.za>
Merge pull request #46 from benniel/changes

Various changes and bug fixes
Fixes

-Renamed the WorkerProgress class to NodeManager
-Error handler no longer removes jars from the database if they are still in use by other jobs
-The NodeManager is now responsible for deleting local jar files when they are no longer in the db
-The NodeManager now reports recource (cpu, ram, disk space) info to the database every 10 seconds

Signed-off-by: Bennie Leonard <bennie.leonard@gmail.com>

Signed-off-by: Bennie Leonard <bennie.leonard@gmail.com>
Merge pull request #47 from benniel/fixes

Fixes
Fixed lost samples error due to
a) samba file overwriting not working
b) workers being disconnected when messages are sent

Fixed (?) hanging workers due to error stream not being read which created a deadlock