Changes to support a Guzzle\Http\Parser namespace

[Common] Adding keySearch method to Collection
[Http] Moving POST curl option logic from EntityEnclosingRequest to the
curl factory method
Directly using the HTTP request object when creating curl handles in the
factory method
No longer adding a read callback when sending POSTs through
CURLOPT_POSTFIELDS
In an effort to mitigate random segfaults and bus errors, using a queue
for removing curl and close handles from a multi object so that they are
only removed when the multi handle has finished sending all requests.
Calling reset() each time a curl multi handle has finished all requests.
EntityEnclosingRequest::getPostFields() now returns a Collection object
Simplifying the EntityEnclosingRequest::getPostFiles method
Adding an array cache to header objects
Moving the header comparison DSL from the Tests namespace to
Guzzle\Http\Message\HeaderComparison, and adding tests.
Adding message, cookie, and url parser interfaces and default
implementations.
Using a parser registry to manage globally registered parsers.  Removing parsing from Response and RequestFactory.
Renaming protocol_version to version
Changing the Guzzle\Http\Message\Response::setProtocol() method to accept a protocol and version in separate args.
Simplifying the chunked encoding handling in RequestFactory
Moving cookie parsing out of the cookie plugin and into Guzzle\Http\Parser\Cookie\CookieParser
Removing regexps from the cookie parser and simply using stripos
Moving the parseQuery method out of Url and on to QueryString::fromString() as a static factory method.
Adding more logging to node.js test webserver
Adding pecl_http message parser.
Installing pecl when travis boots up
Performance improvement.  Using variable function rather than call_user_func() for type checks.
Moving getUrlPartsFromMessage from a static method to an abstract class
Refactoring service builders and service factories

[BC] [Service] Moving Guzzle\Service\Builder to
Guzzle\Service\Builder\ServiceBuilder
[Service] Creating an AbstractFactory used to delegate class
instantiation to a concrete factory. Used with service builders and
service descriptions
[Service] Making service descriptions and builders cacheable
[Service] Adding the ability to set global option overrides to service
builder configs. These options are applied to each service owned by a
service builder.  This can be used to globally specify access keys for
example.
[Service] Adding the ability to include other service builder config
files from within XML and JSON files.
[Service] Changing the format of XML and JSON configs.  Old format still
works too.
[Service] Moving XML service description includes to the end of
execution, so that includes are at the beginning of the parsed array.
[Service] Adding a Guzzle\Service\JsonLoader for loading JSON files that
have an { "includes": [] } array
[Http] Moving UriTemplates to Guzzle\Http\Parser\UriTemplate namespace (hoping for a C implementation at some point for PHP).
Reafactoring Cookie parsing a bit
Trimming up the default User-Agent header and putting entries in order of importance
[Http] Optimizing getTokenizedHeader
Adding an addRequest method to the BatchQueuePlugin.  Fixing a docblock for CurlMulti
Adding a CHANGELOG.  Fixes #52.
Bumping version number