Edit `BoundedNumericProperty.check` to use "%f" rather than "%d" for float max/min in ValueError error message.

If the supplied value is outside the bounds of BoundedNumericProperty, a ValueError is raised by `BoundedNumericProperty.check`.  However, the error message inside the ValueError is incorrect if the max or min are floats, since the error message uses "%d" rather than "%f".

This means for example that if the min is 0.6 and you supply a value of 0.4, the error message will tell you that your value was below the minimum bound of "0", which is incorrect for 2 reasons.
Made UrlRequest decoding optional with parameter
Stopped empty accordian from accessing its first child when initialized
Clear version change documentation

The documentation of [RelativeLayout.py] (https://github.com/kivy/kivy/blob/master/kivy/uix/relativelayout.py#L21) says:

    .. versionchanged:: 1.7.0

        Prior to version 1.7.0 The :class:`RelativeLayout` was implemented as a
        :class`FloatLayout` inside a :class:`Scatter`.  This behaviour/widget has
        been renamed to `ScatterLayout`.  The :class:`RelativeLayout` now only
        supports relative position (and cant be roatated or scaled), so that the
        implemetation can be optimized and avoid the heavier calculations from
        :class:`Scatter` (e.g. inverse matrix, recaculating multiple properties,
        etc)

I was struggling why is it that it says it cannot be rotated or scaled?. I had a `Widget` that inherits from `RelativeLayout` in which I was able to `Rotate` and `Scale` without any problem. It took me quite a while to find out that the documentation only refers to multi-touch behaviour.
Added Spinner widget's kv lang to style.kv
Merge pull request #1262 from abhijangda/spinner

Added Spinner widget's kv lang to style.kv
Merge pull request #1249 from Aaron1011/empty_accordian_crash

Stopped empty accordian from accessing its first child when initialized
Update packaging-android.rst
two minor typos
fixed slightly awkward grammar
linked gihub source code, missing full stop
English idiom, missing full stop
English idiom
typo, linked to wikipedia for event programming
typos
typos
typos, removed all full stops for consistency
extra space, like->such as
graphics: use destructor callback in ref() to avoid self.gc. ref #1270
Merge branch 'enhance-graphics-gc'