v1.0.0-beta2

UPDATES:

• Issue #51: Fix composer dep declarations for easy install
• Issue #54: Fix bug preventing redirect if request method was not GET or HEAD
• Migrate to amphp framework

BC BREAKS:

• Because the library has been migrated to the amphp concurrency framework all Artax namespace
  declarations in your code must be updated to Amp\Artax. Additionally, return values from both
  Client::request() and Client::requestMulti() now implement Amp\Promise (was After\Promise).