Fix for build state effect bug, and addition of subtle flashing effect.

Hi,

We've been trying to use this plugin for our build monitors at one of EA's internal studio's but had issues with jobs not correctly updating state, and developers finding the white flashing builds distracting.

As such I identified and resolved a bug related to removing the flashing build effect jobs, and also implemented a 'subtle' version which changes opacity rather than flashing white which seems to be much less distracting.

If would be great if you could take a look at these changes and maybe pull them.

Thanks,

Simon Watmough