Relax float param validation

If we can convert it to a decimal, we call it good enough.
This means that ints, and numbers as strs "123.245" can be
used.  This also gets around float precision loss.

Fixes aws/awscli#197.
Decode response body before parsing json

The encoding argument is deprecated in python3
and fails silently:

The ``encoding`` argument is ignored and deprecated.

So instead the bytestring is decoded before being handed
off to the json parser.
Use the passed in encoding
Merge branch 'json-utf8' into develop

* json-utf8:
  Use the passed in encoding
  Decode response body before parsing json
Merge branch 'float-validate' into develop

* float-validate:
  Relax float param validation
Add set_stream_logger method to botocore

Update the debug logger to internally call set_stream_logger.
py26 fix, stream kwarg does not exist
Merge branch 'add-logger-method' into develop

* add-logger-method:
  py26 fix, stream kwarg does not exist
  Add set_stream_logger method to botocore
Bumping version to 0.15.0
Merge branch 'release-0.15.0' into develop

* release-0.15.0:
  Bumping version to 0.15.0
Change readme from md to rst
Bumping version to 0.15.1
Merge branch 'release-0.15.1' into develop

* release-0.15.1:
  Bumping version to 0.15.1