display status of job nodes

[ccraddock]

• front end should receive a list of all nodes for a job when the job begins to execute - a separate message is received for each node
• front end should receive a message every time a node changes state, states are (this needs to be verified): ready -> running -> error -> finished
• in the frontend, in the execution status page, modify the matrix of jobs, so that when you click on the job it will show a matrix with all of the nodes and their current state
• the node color should correspond to the status, using the same color scheme as the job matrix
• clicking on the node should display the available information for that node, which should include, node name, start time, finish time, how much memory it used, and how many threads it used