Changed derivative graph to show value per second

The derivative graph used to show value per ms,
I have changed it to show the value per second.
Added timestamp check for #safePlot

the safe plot method now checks if the timestamp is in ms or seconds.
If it is in ms it multiplies by 1000.
cassandra derivative graphs now use DerivativePlot class
added safeplot for latency graph
Merge pull request #114 from dzautner/fix-cassandra-tab

Fix cassandra tab
Changed JVM graphs to take # of ticks from settings

JVM graphs now take the # of ticks to dispaly from settings.
Also, the max # of ticks is raised to 80, presenting a longer history.
Merge pull request #117 from dzautner/extend-jvm-graphs

Changed JVM graphs to take # of ticks from settings
Fixed JVM graphs data slicing
Merge pull request #118 from dzautner/fix-jvm-graphs

Fixed JVM graphs data slicing
moved labels below graph
added new label position to other graph types
removed time label from all graphs
removed graph title from cassandra graphs
added proper title to side text graph boxes
fixed labels in side text graph
fixed sidetext graph boxes labels
Merge pull request #119 from dzautner/move-graph-labels

Move graph labels