Basis of Presentation and Summary of Significant Accounting Policies - Net loss per share - Anti-dilutive securities (Details) - shares	9 Months Ended
	Jan. 31, 2016	Jan. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	7,439,588	5,114,787
Common stock equivalent of convertible notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	0	240,000
Common stock equivalent of convertible notes - related parties
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	27,210	51,020
Series A Preferred Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	0	1,566,500
Series B Preferred Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	6,691,170	0
Warrant
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	712,875	2,975,775
Common shares reserved for series A preferred share dividends
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	0	24,912
Stock-Based Compensation
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	8,333	256,580