Adding support for 'timeEvent'

[mayurdhurpate]

Mxpanel has a useful feature of timing events by calling timeEvent when the event starts. Would like to have this feature in Mixpanel. I can also try and submit a PR if the package is active?

[cloudbomber]

#19

[mayurdhurpate]

Wow, that's great! Would be great to have this merged soon.

[mayurdhurpate]

@surenyonjan @proteye would be great if we could have this merged. An important tracking feature for us too.