Handoff Error Check & Routing

Fixes 2 small issues: 
-Handoffs that were drawn b/t events right on top of each other would fire an error (solves #138 )
-Handoffs drawn between two close events had some awkward pixel misalignment (see photo)

Original: 
![screen shot 2014-12-16 at 1 46 58 am](https://cloud.githubusercontent.com/assets/1930207/5451623/cdc423d2-84c6-11e4-8078-feaac5cc9e40.png)

Post-Fix: 
![screen shot 2014-12-16 at 1 46 42 am](https://cloud.githubusercontent.com/assets/1930207/5451621/ca40c418-84c6-11e4-856c-0fb2b09b62bf.png)


To test, simply play around drawing handoffs. Try with different event types and start times. Also make sure to try drawing handoffs between events that were drawn and then dragged. Also try with events that had time edited by the modal form.