Model URIs only, and move alternate request targets to Request's request-line

Merge pull request #18 from weierophinney/feature/uri-refactor

Model URIs and move request-target details to Request

Immutability + URI interface

Immutability + URI interface

0.5.1 - No More Null Streams

• null is no longer allowed (per the ML; see also php-fig/fig-standards#367).

0.5.0 - Selective Mutability

• Refactors MessageInterface to only provide getters.
• MessageInterface now defines getBody() to require that it return a
  StreamableInterface instance.
• Removes Request and Response interfaces
• Provides server-side interfaces:
  • IncomingRequestInterface, which provides accessors for HTTP
    properties and environment-specific items ($_SERVER, $_GET, $_POST,
    $_FILES, $_COOKIE, etc), and support for mutable "attributes".
  • OutgoingResponseInterface, which provides both accessors and
    mutators for all HTTP properties.
• Provides client-side interfaces:
  • OutgoingRequestInterface, which provides accessors and mutators for
    all HTTP properties.
  • IncomingResponseInterface, which provides accessors for HTTP
    properties.
• StreamableInterface removes attach().

0.4.0

• Removed references to RFC 2616 (php-fig/fig-standards#346)
• Added @throws annotations (php-fig/fig-standards#345)
• Clarify MessageInterface::getHeaders() (php-fig/fig-standards#347)
• Whitespace!!! (php-fig/fig-standards#351)
• Clarify MessageInterface header methods (php-fig/fig-standards#353)
• Clarify superglobal usage (php-fig/fig-standards#354)
• Clarifications in language. (php-fig/fig-standards#356)

0.3.0

Merge pull request #4 from weierophinney/feature/psr7-incoming-request

[PSR-7] Updates based on changes to proposal