Add Delay#reconfigure method

allows to replace the block evaluating to the value with new one
only if a delay is still incomplete?
Fix configuration to be thread safe

by replacing ||= operator with Delay instances
remove unsafe mutex from configuration
Fix processor count

use Delay same as in configuration
extract pool initialization to methods
remove early pool initialization
Merge pull request #90 from jdantonio/operator

reopening "Add Delay#reconfigure and Fix configuration to be thread safe"