Note 13 - Employee Equity Incentive Plans - Stock Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of shares (in shares)	1,225,000	2,002,500
Weighted average exercise price (per share) (in dollars per share)	$ 0.17	$ 0.14
Weighted average remaining contractual term (in years) (Year)	4 years 32 days	2 years 226 days	1 year 146 days
Aggregate intrinsic value	$ 130,475	$ 83,425	$ 198,990
Number of shares, granted (in shares)	4,650,000	450,000
Weighted average exercise price (per share), granted (in dollars per share)	$ 0.26	$ 0.20
Number of shares, exercised (in shares)	(300,000)	(1,120,000)
Weighted average exercise price (per share), exercised (in dollars per share)	$ 0.13	$ 0.12
Number of shares, forfeited/cancelled/expired (in shares)	(300,000)	(107,500)
Weighted average exercise price (per share), forfeited/cancelled/expired (in dollars per share)	$ 0.14	$ 0.29
Number of shares (in shares)	5,275,000	1,225,000	2,002,500
Weighted average exercise price (per share) (in dollars per share)	$ 0.26	$ 0.17	$ 0.14
Vested and exercisable at December 31, 2017 (in shares)	400,000
Vested and exercisable at December 31, 2017 (in dollars per share)	$ 0.19
Vested and exercisable at December 31, 2017 (Year)	1 year 153 days
Vested and exercisable at December 31, 2017	$ 32,638