further improve spark status

[scottdraves]

• remove the big margin to the right of "Connected".
• no decimals in the storage memory box. show integers 0-999, followed by KB, MB, GB, etc. do not not show "B" by itself, if it's that small show "0 KB".
• hover over "x" says "Stop Spark Session".
• increase the gap between the "connected" button and the 3 status numbers, make it about the same as the gap from the numbers to the "x".

[vishnu2kmohan]

Don't mean to hijack this issue but (thanks and kudos to) @krishnan-r has put together an impressive Spark Monitor at https://github.com/krishnan-r/sparkmonitor and we stand to benefit from a joint collaboration to implement his feature set esp. the timeline view, overall executor count/status and UI proxy for the BeakerX JVM Kernels.

[scottdraves]

yea that looks even better, would love it.