Allow for undo burst functionality (#36)

[colebillys19]

Implemented 'undo burst' functionality (issue desmosinc#36).

Summary:

• added functions to get and set calculator state to the calc-helpers file
• mapped frame and frameIDs (from the images state slice) to the Burst component's props
• changed the Burst component's local state to include prevFrames, prevFrameIDs, and prevCalcState to allow for undo
• in handleRequestBurst, im grabbing these three values prior to burst capture
• if the capture is successful, the data is saved in local state
• if unsuccessful, data is not saved
• also added isCapturing to local state to trigger UI change when burst is being captured... capture button changes to 'capturing...' and is unclickable
• when a burst has been captured, an undo button appears in the UI
• added undoBurst action creator, UNDO_BURST action type
• added handleUndoBurst method, dispatches action and reverts calculator

[misscoded]