Share-Based Payments (Details 2) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended	12 Months Ended
	Jan. 31, 2015	Apr. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding, Beginning Balance	23,351,037
Shares, Granted	1,093,175
Shares, Exercised	(3,750)
Shares, Forfeited	(101,250)
Shares, Expired	(349,204)
Shares, Outstanding, Ending Balance	23,990,008	23,351,037
Shares, Vested and expected to vest	23,990,008
Shares, Exercisable	17,031,966
Weighted Average Exercise Price, Outstanding, Beginning Balance	$ 1.01
Weighted Average Exercise Price, Granted	$ 0.72
Weighted Average Exercise Price, Exercised	$ 0.49
Weighted Average Exercise Price, Forfeited	$ 0.96
Weighted Average Exercise Price, Expired	$ 1.04
Weighted Average Exercise Price, Outstanding, Ending Balance	$ 1.00	$ 1.01
Weighted Average Exercise Price, Vested and expected to vest	$ 1.00
Weighted Average Exercise Price, Exercisable	$ 0.91
Weighted Average Remaining Contractual Term, Outstanding (in years)	6 years 7 months 6 days	7 years 6 months
Weighted Average Remaining Contractual Life (Years), Granted	5 years 10 months 24 days
Weighted Average Remaining Contractual Life (Years), Vested and expected to vest	6 years 7 months 6 days
Weighted Average Remaining Contractual Life (Years), Exercisable	5 years 9 months 18 days
Aggregate Intrinsic Value, Outstanding, Beginning Balance	$ 985
Aggregate Intrinsic Value, Granted	0
Aggregate Intrinsic Value, Outstanding, Ending Balance	63	985
Aggregate Intrinsic Value, Vested and expected to vest	63
Aggregate Intrinsic Value, Exercisable	$ 62
Non-Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding, Beginning Balance	765,000
Shares, Granted	80,000
Shares, Exercised	0
Shares, Forfeited	0
Shares, Expired	(150,000)
Shares, Outstanding, Ending Balance	695,000
Shares, Vested and expected to vest	695,000
Shares, Exercisable	487,500
Directors and Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding, Beginning Balance	22,586,037
Shares, Granted	1,013,175
Shares, Exercised	(3,750)
Shares, Forfeited	(101,250)
Shares, Expired	(199,204)
Shares, Outstanding, Ending Balance	23,295,008
Shares, Vested and expected to vest	23,295,008
Shares, Exercisable	16,544,466