Docs clean up part 1

Big push on getting the docs cleaned up before 1.0. Proper wrapping of
everything so it's decently viewable from the command line (or as
decently viewable as markdown can be - the tables will never look great
from the command line).

Only one code change in this PR: rename bouncetime to bounce_time
(everything else is PEP-8, so this probably should be too) and change
its units to seconds from milliseconds (again, all other durations in
the library are in seconds, so it feels inconsistent that this one
isn't; for the sake of those who won't read the docs - which is most
people - I figure consistency helps with guessing!).

gpiozero/output_devices.py

@@ -14,7 +14,11 @@ class OutputDeviceError(GPIODeviceError):
 
 class OutputDevice(GPIODevice):
     """
-    Generic GPIO Output Device (on/off).
+    Represents a generic GPIO output device.
+
+    This class extends `GPIODevice` to add facilities common to GPIO output
+    devices: an `on` method to switch the device on, and a corresponding `off`
+    method.
     """
     def __init__(self, pin=None):
         super(OutputDevice, self).__init__(pin)
@@ -46,7 +50,12 @@ class OutputDevice(GPIODevice):
 
 class DigitalOutputDevice(OutputDevice):
     """
-    Generic Digital GPIO Output Device (on/off/toggle/blink).
+    Represents a generic output device with typical on/off behaviour.
+
+    This class extends `OutputDevice` with a `toggle` method to switch the
+    device between its on and off states, and a `blink` method which uses an
+    optional background thread to handle toggling the device state without
+    further interaction.
     """
     def __init__(self, pin=None):
         super(DigitalOutputDevice, self).__init__(pin)
@@ -125,6 +134,10 @@ class DigitalOutputDevice(OutputDevice):
 class LED(DigitalOutputDevice):
     """
     An LED (Light Emmitting Diode) component.
+
+    A typical configuration of such a device is to connect a GPIO pin to the
+    anode (long leg) of the LED, and the cathode (short leg) to ground, with
+    an optional resistor to prevent the LED from burning out.
     """
     pass
 
@@ -132,6 +145,9 @@ class LED(DigitalOutputDevice):
 class Buzzer(DigitalOutputDevice):
     """
     A digital Buzzer component.
+
+    A typical configuration of such a device is to connect a GPIO pin to the
+    anode (long leg) of the buzzer, and the cathode (short leg) to ground.
     """
     pass