Feature: Flag to run once immediately

[gunar]

Sometimes I don't want to have to wait interval before the first call, so intervals should be

1. "Now+0*Interval"
2. "Now+1*Interval"
3. "Now+2*Interval"

instead of

1. "Now+1*Interval"
2. "Now+2*Interval"
3. "Now+3*Interval"

I propose an option like options.runImmediately = true.

What do you think?

[andyfleming]

I've added support for this as the default in the 2.0 prototype.