Cleanup gemspec
Add rspec tests for the existing method.
Add DeadMansSnitch.report_with_time.

This will allow one to pass a block which will be executed before
reporting to dead mans snitch. This method will also report the running
time of the block and the result to dead mans snitch.
Merge pull request #3 from hwartig/master

Add DeadMansSnitch.report_with_time.