extended VolleyError for more error infos
ImageRequest.doParse() now adds NetworkResponse to all ParseError created

This will help the caller to debug which image couldn't be parsed by
peeking at the NetworkResponse. doParse() already returns the
NetworkResponse of bitmaps successfully parsed, adding it to failed bitmaps
should not take too much overhead.

https://android-review.googlesource.com/#/c/63920/
Support no-content (204) requests in BasicNetwork.

When we get an empty response for say, a 204, we create a 0 byte
response and pass it on to the NetworkResponse. Implementers
of Request can then return appropriate Responses. The behavior
before this change results in an NPE because we attempt to
getContentLength() bytes from a null entity..

https://android-review.googlesource.com/#/c/65325/
make all 2xx be a valid success codes

https://android-review.googlesource.com/#/c/67560/
Fix default image not displaying prior to load

Previously, if a default image was set, it would not be displayed
until a network load had begun. In some use cases where the load
would not be started until some arbitrary time in the future, this
would leave an empty image view visible to the user. This patch
checks to see if there is a default image set, and if so, uses that
to clear the view, so prior to loading, the defualt image will be
shown.

https://android-review.googlesource.com/#/c/69182/
nonblocking DiskBasedCache

https://android-review.googlesource.com/#/c/63630/
Added fitInside parameter to ImageLoader and ImageRequest

The fitInside parameter specifies whether the loaded image
should be scaled to fit completely inside the desired height
and width, or scaled so that it is just large enough to
fill the desired height and width while still maintaining
the aspect ratio.

https://android-review.googlesource.com/#/c/64161/
HTTP headers are case insensitive per RFC 2616 §4.2 "Message Headers"

https://android-review.googlesource.com/#/c/62252/