Replace Date Component Calculation with  timeIntervalSinceDate  Method
Replace Date Component Calculation with  timeIntervalSinceDate  Method

Signed-off-by: Henry McGilton <7c0782145794e960acce451ba04a8f5d8a744f8c@ymedialabs.com>

andyvand/mPower,syoung-smallwisdom/mPower,ResearchKit/mPower,Sage-Bionetworks/mPowerSDK,EricSiegNW/mPower,Erin-Mounts/mPower,Sage-Bionetworks/mPowerSDK,Erin-Mounts/mPowerSDK,Sage-Bionetworks/mPower,Erin-Mounts/mPowerSDK