fix ArrayIndexOutOfBoundsException when sDots[][] index >= length

[buffermet]

When changing the pattern dot count using setDotCount() PatternLockView.java throws an ArrayIndexOutOfBoundsException because sDots is not updated when setDotCount() is called.

Changelog:

• sDots is changed to a private static Dot[][] of PatternLockView class.
• sDots is updated to a new Dot[][] of the appropriate dotCount size.

closes https://github.com/aritraroy/PatternLockView/issues/10