Adding invertPWM option to support basic h-bridge

Necessary for motor controllers that do not invert PWM value on
h-bridge when digital pin is set to high.

Previously PR #367
Relay API aliases: open => off, close => on

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>
v0.7.52

- Motor
  - invertPWM for DIY H-Bridge
- Relay
  - Aliases: open => off, close => on

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>
Gruntfile: copy new version to clipboard

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>
Fix missing global

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>