Share-Based Payments (Details 2) - USD ($)	12 Months Ended
	Apr. 30, 2015	Apr. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding, Beginning Balance	23,351,037	13,890,205
Shares, Granted	21,160,562	9,793,332
Shares, Exercised	(3,750)	(33,750)
Shares, Canceled	(19,872,875)	0
Shares, Forfeited	(151,250)	(72,500)
Shares, Expired	(435,704)	(226,250)
Shares, Outstanding, Ending Balance	24,048,020	23,351,037
Shares, Vested and expected to vest	24,048,020	23,351,037
Shares, Vested	17,111,080	13,564,577
Weighted Average Exercise Price, Outstanding, Beginning Balance	$ 1.01	$ 0.85
Weighted Average Exercise Price, Granted	0.66	1.23
Weighted Average Exercise Price, Exercised	0.49	0.63
Weighted Average Exercise Price, Canceled	1.04	0
Weighted Average Exercise Price, Forfeited	0.96	0.82
Weighted Average Exercise Price, Expired	0.99	0.73
Weighted Average Exercise Price, Outstanding, Ending Balance	0.48	1.01
Weighted Average Exercise Price, Vested	$ 0.49	$ 0.85
Weighted Average Remaining Contractual Term, Outstanding, Beggining Balance (in years)	7 years 6 months	7 years
Weighted Average Remaining Contractual Term, Outstanding, Ending Balance (in years)	6 years 8 months 12 days	7 years 6 months
Weighted Average Remaining Contractual Life (Years), Vested and expected to vest	6 years 8 months 12 days	7 years 6 months
Weighted Average Remaining Contractual Life (Years), Vested	5 years 10 months 24 days	6 years 1 month 6 days
Aggregate Intrinsic Value, Outstanding, Beginning Balance	$ 985,000	$ 89,000
Aggregate Intrinsic Value, Outstanding, Ending Balance	4,166,000	985,000
Aggregate Intrinsic Value, Vested and expected to vest	4,166,000	985,000
Aggregate Intrinsic Value, Vested	$ 2,879,000	$ 927,000
Non-Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding, Beginning Balance	765,000	765,000
Shares, Granted	80,000	0
Shares, Exercised	0	0
Shares, Canceled	0	0
Shares, Forfeited	0	0
Shares, Expired	(150,000)	0
Shares, Outstanding, Ending Balance	695,000	765,000
Shares, Vested and expected to vest	695,000	765,000
Shares, Vested	487,500	522,292
Directors and Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding, Beginning Balance	22,586,037	13,125,205
Shares, Granted	21,080,562	9,793,332
Shares, Exercised	(3,750)	(33,750)
Shares, Canceled	(19,872,875)	0
Shares, Forfeited	(151,250)	(72,500)
Shares, Expired	(285,704)	(226,250)
Shares, Outstanding, Ending Balance	23,353,020	22,586,037
Shares, Vested and expected to vest	23,353,020	22,586,037
Shares, Vested	16,623,580	13,042,285